At least five people have been wounded in the Venezuelan capital of Caracas during street clashes between supporters of President Hugo Chavez and city police.

Chavez is popular with millions of poorer voters

The violence - the most serious since a failed coup against President Chavez in April - started after armed gunmen ambushed a police patrol in a poor Caracas area.

One police officer and four civilians were wounded when police responded with tear gas, and about 1,000 members of the National Guard have been later sent to patrol the capital.

The protests were sparked by a Supreme Court decision on Wednesday to postpone a ruling whether to try four high-ranking military officials accused of involvement in the coup.

Mr Chavez's supporters demand punishment for the officers and have warned of more violence if the court decides against the trial.

They also want mayor of Caracas Alfredo Pena, who is a leading opponent of the president, to resign over the way police responded to the demonstrations.

Political tensions have been rattling Venezuela since the 11 April coup during which President Chavez was briefly ousted from the office.

But he was quickly restored to power by army factions loyal to him.

Divided country

Caracas police chief Henry Vivas said violence erupted when the gunmen with high-calibre weapons opened fire on the police patrol in the impoverished district of the city.

More than 50 people died during the April coup

"It was a well-organised attack, a very intensive attack," Mr Vivas told the Associated Press news agency.

Shops and underground stations in the area were closed, as protesters used buses and lorries to block streets.

Interior Minister Diosdado Cabello said the troops had been deployed to keep the peace.

Caracas has seen sporadic violence earlier this week, and the country remains deeply divided between the supporters and opponents of President Chavez.

Both sides blame each other for more than 50 deaths during the coup and riots that followed.

Mr Chavez's opponents accuse him of driving Venezuela into recession.

But millions of poorer voters still see the president - a fiery former paratrooper - as the only leader capable of improving their living standards in the oil-rich country.