Lagos, Nigeria ? Riot police fired live rounds and tear gas Monday to disperse angry mobs in Nigeria’s commercial capital as fighting erupted between workers over whether to continue an eight-day strike against fuel price increases.

Union officials said at least 10 people were killed during the clashes in Lagos, but police could not confirm that and denied responsibility for any deaths.

President Bush is scheduled Friday to visit Nigeria as part of his five-day, five-nation African tour. Nigeria is Africa’s largest oil producer and the fifth-biggest supplier of crude to the United States.

Nigeria’s main trade unions launched the strike to protest a 50 percent increase in fuel prices ordered June 20 by President Olusegun Obasanjo. That pushed gasoline prices to $1.18 a gallon.

The government says the increase is necessary to end shortages and curb the smuggling of cheap Nigerian fuel to neighboring countries. Despite Nigeria’s great petroleum resources, most of its 126 million people live in desperate poverty.

An umbrella group of administrative workers’ unions pulled out of the strike Sunday after talks with the government.

“We don’t want the agony caused by the strike to continue,” Sina Luwoye, president of the Trade Union Congress, said Monday.

Angered strike backers took to Lagos’ streets, smashing windshields, lighting bonfires and attacking buses taking people to work. When police in protective clothing fired tear gas and bullets over their heads, they melted away, only to regroup elsewhere.

“They’re everywhere trying to cause trouble, molesting people going about their business, but we’ll deal with them,” Lagos police spokesman Emmanuel Ighodalo said.

Adams Oshiomhole, head of the blue-collar Nigeria Labor Congress, said police shot dead at least 10 protesters. Police denied that, saying they had no information on any casualties.

By midday, police officials said they had brought the situation under control, and streets in Lagos were visibly calmer.