Venezuelans have voted to lift limits on terms in office for elected officials, allowing President Hugo Chavez to stand for re-election.

Mr Chavez has said he needs to stay in office beyond the end of his second term in 2012 so he can secure what he calls Venezuela's socialist revolution.

Critics say the that would concentrate too much power in the presidency.

More than 16 million Venezuelans were eligible to take part in the vote, which observers said was free and fair.

Under existing constitutional rules, the president was limited to two six-year terms in office, which meant that Mr Chavez would have had to leave the presidency in 2012.

A proposal to end presidential term limits was one of a package of 69 constitutional changes narrowly rejected in a referendum in late 2007.