Carter, who since leaving office in 1981 has gained a reputation as a political trouble-shooter in world conflicts, arrived Saturday to try to defuse tensions and foster dialogue following a chaotic but short-lived April coup against Chavez.

He immediately encountered the feverish political feuding between opposition and government that has kept the world's fifth largest oil exporter on tenterhooks since the April coup, in which more than 60 people were killed in street violence.

Hours after Carter flew in, Venezuelan opposition parties and groups made a public appeal to him to extend his scheduled four-day visit until Thursday, when anti-Chavez demonstrators are planning a big protest march to the presidential palace.

``President Carter: Stay among us until July 11 and help to guarantee our safety as we take to the streets seeking justice, peace and democracy,'' the opposition groups said in a joint open letter published yesterday in major newspapers.

They said government supporters would not dare to attack them if Carter and his aides observed next week's march.

Foes of Chavez, a left-wing former paratrooper who has ruled since 1998, blame him and his supporters for the deaths of at least 17 unarmed civilian protesters and bystanders who were shot by gunmen in a huge anti-government march April 11.

Chavez blames the opposition for the killings, which triggered the coup by disgruntled military officers who briefly deposed him. He was restored 48 hours later by loyal troops.

Carter, who met the president over dinner late Saturday and held separate meetings yesterday with government officials, the opposition and other social groups, did not immediately respond to the call to stay on in Venezuela for the July 11 march.

In a written statement on his arrival, he said he hoped to persuade Chavez's government and its opponents to engage in constructive talks. Since April, Venezuela has been gripped by fears of another coup and further political violence.

``I'll do the best I can,'' Carter told leaders of Venezuela's Catholic Church as he began talks with them.

Critics of Chavez, who include labour and business chiefs and dissident military officers, have accused the Venezuelan leader of steering his oil-rich country towards totalitarian rule and destroying jobs and investment with his left-leaning policies.

He says his self-proclaimed ``revolution,'' which has included land and credit grants for underprivileged families, is aimed at improving social justice in a nation where chronic poverty and unemployment have persisted despite massive oil resources.

Carter made a headline-making visit last month to communist-ruled Cuba, where he criticized the long-running U.S. trade embargo on the island and urged Cuban President Fidel Castro to introduce more political freedoms.

In contrast, he has adopted a low-key approach for the visit to Venezuela, where a dialogue attempted by Chavez with his foes after the coup has collapsed amid bitter squabbling over who should take the blame for the April killings.

Carter's aides said neither he nor they would make public statements until the end of the trip.

Critics of Chavez have expressed deep skepticism over whether the former U.S. president will be able to bring the government and opposition together in a meaningful dialogue.

Opponents of the president say that although he has toned down his past confrontational style he shows no sign of heeding their calls for him to radically reverse his policies.

In their letter to Carter, the opposition groups said several minimum conditions were required for a dialogue.

They called for the government to disarm groups of its supporters which they say are regularly used to intimidate and attack critics. ``It is not possible to hold a dialogue with coercion and threats,'' the letter said.

It also called for the setting up of an independent Truth Commission to investigate the April 11 killings.

In an interview published yesterday, the U.S. ambassador to Caracas, Charles Shapiro, expressed concern about democracy in Venezuela and the political divisions in the country.

``It's a democracy with problems. It's not a full democracy,'' the daily El Universal quoted Shapiro as saying.