By Adam Easton BBC correspondent, Caracas

Tens of thousands of Venezuelans have marched through the capital, Caracas, to demand President Hugo Chavez' resignation.

They blame him for the deaths of 17 people who were killed during massive street demonstrations in April.

Instead of a dialogue, Venezuela has two monologues

The deaths of both supporters and opponents of Mr Chavez triggered a coup attempt by rebel military officers who ousted the Venezuelan leader for 48 hours before his restoration by loyal officers.

Many of the opposition marchers, who wore black or waved black flags, blame Mr Chavez for ordering the massacre.

"I'm here to support the majority of Venezuelans to get rid of this killer president that we have. Chavez should quit and leave the country," businessman Fernando Padron told the BBC.

Although opinion polls show Mr Chavez' support has increased to 44% from around 30% since the coup, the bitter divisions that caused the coup remain.

At the same time as the opposition march, Mr Chavez' supporters were marching in other Venezuelan cities.

Chavez : Blames the opposition for stoking coup fears

They back his programme of increased public spending on healthcare and education. They say he is the first Venezuelan president to work for the poor, who make up 80% of the population.

Since his return, Mr Chavez has taken steps to defuse Venezuela's political and economic crisis.

He has replaced controversial members of his cabinet, largely dropped his fiery rhetoric, which included calling his opponents "squalid oligarchs" and created a national commission for dialogue.

But instead of dialogue, Venezuela has two monologues.

E-mail 'campaign'

Both sides blame each other for the deaths of the demonstrators last April.

Mr Chavez says video evidence on that day proves that some of his supporters who were armed with handguns, were not firing at opposition marchers, but in self-defence against security forces.

The official inquiry into the deaths has not yet been made public, but the president's opponents say it cannot be impartial, because it has been led by an attorney-general loyal to the government.

The marches come at a time of heightened political tension in Venezuela, in part fuelled by an e-mail information campaign which warns that another coup attempt is in the offing.

The e-mails, which advise people to stock up on food supplies and weapons, are part of the opposition's campaign to create a climate of instability, the government says.

Discontent in the ranks

Rumours of a possible coup circulate daily in Caracas, although one has yet to materialise.

However, if constitutional means started by opposition parties do not succeed in removing Mr Chavez from office, an attempt cannot be ruled out.

Military analysts say discontent within an already divided armed forces has been worsened by the government's purge of officers involved in April's coup.

A group of retired officers are due to march against the government on Thursday and another potential flashpoint looms on 5 July when military promotions are set to be announced.