Caracas, Venezuela, Feb 20: Venezuela`s opposition appealed to the head of the Organisation of American States to rush to Caracas to stop what they said were President Hugo Chavez`s efforts to block a recall referendum against him. Chavez`s supporters and opponents are locked in a fierce dispute over whether a vote should be held this year on his presidency of the world`s No. 5 oil exporter. The opposition says electoral officials are favoring the president by obstructing approval of a referendum signature petition. Chavez and his supporters say the petition contains tens of thousands of forged signatures. International concern is growing that the conflict could spark renewed upheaval in Venezuela, scene of a brief coup in 2002 followed by a spate of strikes and protests. ``Given the seriousness of the situation, let`s hope the (OAS) secretary general can come, the sooner the better,`` Humberto Calderon, a spokesman for the opposition Coordinadora Democratica Coalition, told reporters. ``I don`t think the OAS will remain silent about what`s happening here,`` said Calderon, who also urged individual foreign governments to send envoys. It was not clear when OAS chief Cesar Gaviria might make the trip. ``He`s on standby, with his bag packed,`` said one Caracas-based diplomat monitoring the referendum process. Observers from the OAS and the Atlanta-backed Carter Center are following the electoral council`s work in checking 3.4 million pro-referendum signatures the opposition says it collected. A minimum of 2.4 million valid signatures is required to trigger a recall vote in May or June. In what opposition leaders say is clear evidence of obstruction, just over 50 percent of the pro-referendum signatures have been retained for further scrutiny by the electoral authorities. Signaling concern over holdups, the OAS and Carter Center last week urged the national electoral council not to dwell on ``excessive technicalities.`` They urged it to meet a February 29 deadline for a referendum decision. The United States, the leading buyer of Venezuela`s oil, has backed this position. Chavez, a populist former paratrooper elected in 1998, this week angrily accused the US government of trying to oust him, a charge denied by Washington. Chavez also warned the OAS and Carter Center not to try to overrule the electoral council. Bureau Report