By Andrew Hammond

MANAMA (Reuters) - Labour activists gathered in the Gulf Arab state of Bahrain this week in a campaign to improve the conditions of millions of migrant workers whose mistreatment has drawn international attention.

Earlier this year construction workers in the United Arab Emirates rioted over unpaid overtime and salary cuts, the latest in a series of disputes in the Gulf region over non-payment of wages, lack of medical care and squalid housing.

The United States has urged the UAE to amend laws to conform to the International Labour Organisation's standards in order to qualify for a proposed bilateral free trade pact.

The riot in March brought into focus the plight of some 11 million workers -- mostly from the Indian subcontinent -- in a region that is experiencing an unprecedented construction boom as oil-dependent economies flourish on high world prices.

Mustapha Said, a senior official of the Building and Wood Workers International (BWI), said labor campaigners will press governments to allow trade unions to help defend worker rights.

"There is a need to defend these exploited migrant workers whether or not they attract attention through strikes or sit-ins," the Lebanese activist told Reuters on the sidelines of the Arab and Asian union gathering which ended late on Friday.

"You can't find any other place in the world with this situation," he said, referring to the large number of unrepresented workers in the Gulf. "It is a new phenomenon."

Gulf governments' fear of long-term residents demanding nationality rights has complicated the workers' cause. Foreigners make up around 85 percent of the UAE population and some 7 million of Saudi Arabia's 24 million population.

"If you don't want to give me nationality that's fine," Said said. "But what about safety, what about giving me my wage at the end of the month, what about moving freely, what about being allowed to change employer, what about allowing me to sue him?"

UNIONS IN BAHRAIN

Bahrain has led the way in giving ground to expatriate labor with legislation in 2002, but many workers are ignorant of union rights and employers try to keep them in the dark.

"Many are afraid they will be kicked out because of intimidation by employers," said Abdulla Hussain, from the General Federation of Bahrain Trade Unions.

So far 50 unions have been set up in companies with 20,000 workers, but only 1,000 of them have joined and most of them are Bahrainis not migrant workers, he said.

Kuwait also allows trade unions, but restricts membership to Kuwaiti nationals, the activists said.

Under intense media glare because of its rapid transformation into a glamorous international destination, the UAE has vowed to set up unions and crack down on abuses in an amended labor law.

The long-term goal of the nascent Gulf labor movement is to end the region's unique "sponsorship" system, which has long been criticized by international human rights groups.

Foreigners can only obtain a visa to work in Gulf countries through a citizen or institution acting as their "kafeel", or sponsor, for a certain fee even though the workers may not find jobs.

Samar Thapa of the General Federation of Nepalese Trade Unions said Asian countries were also to blame.

Agencies charge huge fees to send their countrymen to the Gulf without proper contracts and activists say governments are loathe to raise complaints to ensure earnings from remittances.

Pakistan and the Philippines want to increase their workers in Saudi Arabia, currently around 2.5 million.

"Migrant workers are suffering for the economic progress of the Gulf countries," Thapa said.