Would you buy knowingly buy sportswear from global brands or clothes manufactured at garment factories that exploit largely underpaid young women migrant workers from Myanmar? Probably not, yet finished goods like trainers, sportswear, mosquito nets and other garments are transported by truck day and night to Bangkok from garment and textile factories in and around Mae Sot on the Thai-Myanmar border.

"Lack of citizenship means not just the absence of labour rights and social protection as workers, but also their gendered exclusion from the entitlement to personal security, health and education," she explains in her book.

Kyoko Kusakabe, co-author of "Thailand's Hidden Workforce" (Zed Books, 2012), would love to be able to tell you which brands to avoid but admits that because of the long chain of subcontracts, it's hard, sometimes impossible, to pin down the brands of the goods manufactured in border areas.

"Owners of brand names don't manufacture their products themselves. They subcontract production to factories. These factories further subcontract to smaller plant in border areas. These factories do not put the label so it's hard to tell for which brands these goods are being made. The labour unions are trying to follow these commodities though," she says.

Central to production of these goods at factories in Mae Sot and elsewhere are migrant workers. In garment factories, most workers are women, the subject of Kusakabe's book, also co-authored by Ruth Pearson, professor in international development at the University of Leeds.

Kusakabe is associate professor in gender and development at the Asian Institute of Technology on the outskirts of Bangkok. Her interest in gendered mobility and migration in the Greater Mekong Sub-region brought her together with Pearson to expose the harsh realities of the migrant labour.

"Thailand's Hidden Workforce" focuses on labour issues affecting specifically migrant women workers from Myanmar toiling away in garment factories mainly in Mae Sot in Tak province and the Three Pagoda Pass in Sangkhlaburi. Mae Sot hosts the largest number of women workers from neighbouring Myanmar.

Through her book, Kusakabe tries to lift the lid on the realities faced by women in garment factories where the conditions are "exploitative and difficult.

While child labour has frequently come under the spotlight, the stories of hardship endured by women migrant workers are less known to the world at large and need to be told, she says.

Kusakabe explains that due to globalisation forces, Thailand has lost its competitiveness in the manufacturing sector to countries like China. To boost its competitiveness, Thailand turns to cheap migrant labour, much of it from Myanmar. There are two million migrant workers from Thailand's western neighbour currently working in Thailand in the fishery, agriculture and garment and textile industries. Half of them are registered workers; the other half are considered illegal and subject to deportation.

"Basically I'm interested how women are working and what are their working conditions, says Kusakabe, adding: "Burmese migrant workers are in the fisheries. More women than men go to garment and textile factories in border areas. It is here that Thailand is losing its competitiveness, as cheaper labour markets have emerged in China and Vietnam. Global competition is creating certain groups of workers like the ones I came across in Mae Sot."

There are more than 160 large and small apparel factories in Tak province and more than 100,000 Myanmarese workers. Mae Sot has one of the highest concentrations of migrant workers and the large factories are generally owned and managed by Thai industrialists, working on contracts for major contractors in Bangkok, or directly for foreign global brands.

Work in Mae Sot's garment factories involves sewing up cotton pieces into final garments and fabricating knitted articles from yarn.

In the Three Pagoda Pass area, subcontractors make trainers and other sportswear for global brands, and manufacture mosquito nets and clothing. Raw materials come up from Bangkok and the finished goods are sent back to the capital every day.

Workers are either young, sometimes 15 or below, or older women who migrated when they were already parents. Without proper documentation, it's hard to gauge the actual ages of workers, says Kusakabe. In some cases, workers are children.

With the backup of Thai and Burmese researchers, Kusakabe and Pearson were able to interview these workers.

"We didn't gain access to factories because they didn't allow us in. These factories have Thai and Burmese guards," Kusakabe says.

But the research team was able to interview the workers in their communities and they were left almost speechless by the plight of the women.

Workers need to endure unimaginable working conditions. Garment factories have chosen to relocate to border towns because they want to enjoy advantages that cannot be found in big cities such as cheap labour, lax labour inspections and opportunities for overhead reductions through blatant restrictions of workers' rights and benefits. The work regime at some workshops is intensive, requiring the women to be at their machines from 6am to 9pm with only short breaks for meals.

"Their problems range from reduced pay, late payment and non-payment of wages to restrictions on benefits and rights and total exploitation," says Kusakabe, adding: "Some factories have several deductions so that workers are paid very little. Some get paid Bt100 per day, other might get Bt60 or even less.

"Many are not registered because the registration fees are higher than their salaries. Unregistered workers are abused by their employers in many ways. Many work for months without being paid. And they don't have legal protection because they are not registered workers," she says, adding that less than 50 per cent of the workers surveyed were registered.

In the book, Kusakabe describes how workers suffer forms of abuse and repression. Many remain in debt to the carriers that arranged their journey from home, or to the agents who secured them access to their first employer. Ongoing abuses include illegal imprisonment, beating, sexual assault, threats by employers to report unregistered workers to police and homicide.

According to Kusakabe, workers have to put up with illegal working conditions and tough labour regimes to continue to earn money for themselves and their families. Because of insecurity and the precariousness of the occupation, most workers change jobs frequently, often moving as many as five times in two or three years. If migrant workers have acquired skills in garment factories either at home or in Thailand, they generally try to stick to sewing or machine knitting jobs, but when this is not possible they switch to other types of employment.

Kusakabe recommends an "easier" registration system for better monitoring of labour migration, better legal protection of workers' right and better recognition of children of workers born in Thailand.

Compounding the problem is that many migrant workers don't have ID documents from Myanmar. Stateless they fall prey to unscrupulous employers. "They have been told by their employers not to get pregnant in Thailand," she says.