Venezuelan President Hugo Chavez appeared headed for a narrow win on Sunday in a referendum on scrapping term limits on his rule, government officials said, but opposition leaders said the vote was too close to call.

Exit polls and early counts by party members showed the race tightening with the anti-U.S. leader ahead by as little as four percentage points, senior government officials said. Three ministers who asked not to be named earlier said the margin was between six and eight points.

Vice President Jorge Rodriguez told reporters the vote was close. Opposition politicians also said the outcome was tight and questioned the government's data that put Chavez ahead.

They are trying to create rumors to present themselves as winners, as victors, Andres Velasquez, an opposition leader said. We want to deny it categorically, emphatically.

If approved, the referendum vote on a raft of reforms would allow Chavez -- in office since 1999 -- to run for reelection indefinitely, control foreign currency reserves, appoint loyalists over regional elected officials and censor the media if he declares an emergency.

Chavez has said he wants to rule for life and turn the major oil exporter into a socialist state.

The opposition did not release its own polling data except for an exit poll in Caracas, where they have beaten Chavez in the past. The president is more popular away from main cities.

It's very close, very close, said Julio Borges, the leader of a main opposition party, Justice First.

Most pre-vote opinion surveys predicted a tight vote on the package of constitutional changes that the opposition and even some former longtime allies say is authoritarian.

Pollsters had said a low turnout would favor Chavez, who activated a state-backed get-out-the-vote campaign against an underfunded, fragmented opposition.

The left-wing leader, a fierce critic of the United States and close ally of communist Cuba, has never lost a national vote and had predicted he would win by at least 10 points on Sunday.

SENT BY GOD

Even before any official results were announced, some of Chavez's supporters began to celebrate.

Dressed in red and waving Venezuela's red-blue-and-yellow flag, they danced in the streets and drove cars and motorcycles around Caracas honking horns.

The reform is very important for the country, we want to support our president, said Marlene Vanegas, 70, who described herself as a full-time revolutionary and Chavez loyalist. he was sent to us by God.

One government minister and a close Chavez aide said latest data showed the president's lead was down to four points from as a high as eight points and stood at 52 percent for Chavez and 48 percent for the No camp.

They said the final result could show a wider Chavez victory when the tally takes into account rural areas, where Chavez is popular. Official partial results were due later on Sunday.

Led by a mix of political parties and university students, the opposition had pointed to some pre-referendum polls showing it could win.

It has lost to Chavez in almost yearly national votes and also failed to topple him with a coup in 2002, a national strike and a recall referendum.

Foreign investors worry that the opposition could contest the result if it suspects fraud, sparking political turbulence after a campaign marred by violent street clashes.

(The vote) will deepen divisions and polarization, said Jesus Ghersi, 25, an engineering student serving as an official poll watcher for the opposition.

(Additional reporting by Fabian Andres Cambero, Patricia Rondon and Jorge Silva, Writing by Saul Hudson; Editing by Kieran Murray)

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