CAPE TOWN, South Africa (AP) — Seven people were arrested when police broke up a demonstration of about 200 stewards with rubber bullets and a stun grenade in a labor dispute linked to low pay for World Cup duties.

Police superintendent Andre Traut said no one was injured during Thursday's protest outside the stewards' employer's offices.

Police have taken responsibility for stadium security in Cape Town, both Johannesburg venues, and the grounds in Durban and Port Elizabeth since stewards began protests Sunday night.

Traut said Thursday's gathering in Cape Town was broken up after about two hours in the Ysterplaat neighborhood, far from where most fans gathered on the eve of the England-Algeria game at Green Point Stadium. Those arrested were charged with "participating in an illegal gathering," Traut said.

The main labor federation said police were out of line to take such drastic action.

"Nobody was in danger," union provincial secretary Tony Ehrenreich said in a telephone interview. Instead of breaking up demonstrations, "there should be negotiations," he added.

Privately hired security stewards went on strike over low wages, and police had already taken over their duties on an interim basis before Wednesday's announcement the arrangement will last through the World Cup.

Five of the 10 stadiums have not been affected by the protest.

Soccer City, the largest of the World Cup venues, hosted its first match under police-staffed security when Argentina played South Korea on Thursday. There were no major security issues as Argentina won 4-1.

The protests began Sunday night when police used tear gas and fired rubber bullets to disperse stewards in Durban who were angry about their wages and refused to leave Moses Mabhida Stadium.

But bringing in police from outside could weaken the security networks in many crime-ridden neighborhoods, the labor union (COSATU) said in a statement.

The police "are being taken from the normal policing duties and leaving communities and other areas exposed. Whilst we accept that in urgent circumstances police deployment may happen, authorities can't be relied upon" to resolve all labor issues.

The South African Transport and Allied Workers Union, which represents many security workers, said it asked the Labor Department to investigate whether laws were broken during the recruitment of the security stewards.

According to the union, most of the security workers hired for the World Cup did not have written contracts, were paid less than promised, received inadequate training and were forced to work in substandard conditions.