Paraguayans went to the polls yesterday to elect a new President, with a former Roman Catholic bishop seeking to unseat the Colorado Party after more than 60 years of one-party rule.

Most polls show ex-bishop Fernando Lugo edging out the ruling party's Blanca Ovelar, who is the first woman to run for President, and retired army general Lino Oviedo. But analysts say the race is too close to call.

Isolated fistfights broke out between people supporting rival candidates and hecklers threw pepper gas inside a suburban polling station where Lugo's vice-presidential candidate was voting, a campaign aide said. "This doesn't frighten us or daunt us, we're all very calm," Mgr Lugo told local radio.

The head of the country's electoral tribunal told reporters that, in general, everything was running smoothly. But dozens of international observers are watching for signs of electoral fraud in the poor South American country known for widespread corruption and contraband.

Paraguay's military and about 10,000 police officers were handling security at the roughly 1,000 schools being used as polling stations throughout the country. The candidate who gets the most votes wins the presidency, with no second round of balloting.

Mgr Lugo is heading a centre-left coalition and calls himself an independent. He has steered clear of South America's more radical leftist leaders, such as Venezuela's Hugo Chavez and Evo Morales in Bolivia.

The Colorado Party has dominated Paraguayan politics since 1947, backing General Alfredo Stroessner's 35-year dictatorship until helping to oust him in 1989. The party was weakened by a bitterly divisive primary race, in which accusations of fraud marred Ms Ovelar's victory. A former education minister with little experience in party politics, she has struggled to rally the party around her.

Mr Oviedo jumped in the race for the rightist Unace party after the Supreme Court overturned his 10-year prison sentence for plotting a coup in the mid-1990s. He is mostly backed by poor people who long for the return of a strongman leader.

Ms Ovelar and her mentor, outgoing President Nicanor Duarte Frutos, have rejected the possibility of electoral fraud.

"We believe the people will vote without any problems," Ms Ovelar told a televised news conference early yesterday.

Elma Oviedo, a 70-year-old housewife, said she is thrilled to finally have a woman running for office.