TEGUCIGALPA : Honduran police fired tear gas to disperse thousands of angry demonstrators, as ousted President Manuel Zelaya called on the United States to do more to resolve the crisis.

Zelaya supporters clashed with riot police, who used tear gas and batons to beat back those marching on the national parliament building in the capital Tegucigalpa.

Protesters threw stones and broke the windows of several nearby businesses, ignoring police warnings of a crackdown.

An angry mob attacked a lawmaker known to back the June 28 coup against Zelaya, before police mounted a successful rescue.

Around 50 demonstrators were detained during the clashes, which came a day after rioters torched the local branch of a fast food chain.

In a separate incident in the economic capital San Pedro Sula, stick-wielding protesters formed makeshift road blocks near the hotel of Costa Rica's visiting football squad.

Police responded by firing tear gas and rubber bullets.

As the violent repercussions of the coup was felt on the streets, the diplomatic fallout continued in Latin America's capitals.

Honduras's international isolation deepened as the small Central American country was told it could not attend an upcoming meeting of top regional military brass.

Argentine organizers said the Honduran military would no longer be welcome at the gathering because of its role in the coup that threw Zelaya out of office.

The exiled leader spent the day in Brazil, meeting President Luiz Inacio Lula da Silva as part of a near two-month bout of shuttle diplomacy aimed at garnering support for his return to power.

Zelaya called for greater backing from Washington for his plight and "a firmer (US) position to show that these attacks on democracy cannot be repeated."

But he was at pains to distance himself from the claims of leftist allies that the United States had a hand in his ousting, adding that Secretary of State Hillary Clinton had invited him for another round of talks in Washington.

"I hope to go there in the coming weeks, but nothing has been confirmed for now," said Zelaya.

Latin American leftist leaders and some US lawmakers have criticized President Barack Obama's administration for failing to take a firmer stand against the interim Honduran regime, while some US Republican lawmakers have denied that a coup took place.

Brazilian Foreign Minister Celso Amorim told journalists that Lula had promised the ousted president he was ready to discuss the matter with Obama, who earlier this week reaffirmed that Zelaya was the rightful leader of Honduras, and assailed those who fault his approach.

"The same critics who say the US has not intervened in Honduras are the same people who say we are always intervening and Yankees need to get out of Latin America," Obama said in Mexico on Monday, accusing such opponents of "hypocrisy."

The Organization of American States (OAS) plans to send a delegation of Latin American foreign ministers to Honduras next week to press for a negotiated solution to the crisis.