Hanoi - Some 4,000 workers at a Taiwanese-owned shoe factory in Vietnam's Thanh Hoa province went on strike over the weekend, protesting alleged misconduct by the management in the first wildcat strike of 2009, police and trade union officials said Monday.

"This is the first wildcat strike in our province this year," said Tran Thi Gioi, president of Thanh Hoa province's Trade Union.

"This is a spontaneous wildcat strike because workers are angry about the way management has treated them," said Le Duc Ngoan, a policeman in Quang Hung Commune.

Ngoan said workers reported that Chinese managers of Sun Jade Vietnam, hired by the factory, had beaten and humiliated them several times.

Local media reported that each worker is granted a pass to travel through the factory's workshops. When arriving late the managers often cut their passes in half, forcing the workers to purchase new ones for 150,000 dong (9 dollars) as punishment.

Those arriving late were also docked that day's wages and were not allowed into the canteen to eat the lunch provided to them by the factory. They also claim to have not been allowed to leave and buy lunch outside the premises.

The workers said they had reported abuses to top management many times, but were met with silence. As a result, strikes began Saturday. Factory owners then promised to solve the problems.

Workers returned to work Sunday only to strike later in the day after floor managers began reprisals. The managing board has said it will take action against those harassing workers. By Monday, most had returned to work.

"We will continue to strike in the next few days if our requests are not met," said a worker who declined to be named, fearing retribution.

"We have coordinated with the trade unions to reconcile workers and factory management," said Ngoan. "Most have returned to work today."

In Vietnam strikes must be approved by both local authorities and trade unions before going ahead. Few are approved.

Sun Jade Vietnam Company has six factories with a total of 30,000 workers in Vietnam. The Thanh Hoa factory has 4,500 workers earning between 1.2 million dong (71 dollars) to 1.5 million dong per month.

Vietnam reported 650 wildcat strikes last year, compared with 541 in 2007. Strikes have been on the rise after last year's rapid inflation, which rose by 23 per cent in 2008, year-on-year. Prices for foodstuffs rose by 42.4 per cent. (dpa)