BOGOTA: Colombia's Constitutional Court on Friday announced it rejected a bid by President Alvaro Uribe for a third consecutive term in office, a ruling Uribe said he would honour.

Lead justice Mauricio Gonzalez said that the high court declared that the law calling for a referendum that would have allowed a third term "cannot proceed."

"The anomalies (of the law) seen as a whole constitute a grave violation of democratic principles," Gonzalez said.

Uribe, Washington's closest ally in South America, was first elected in 2002 and easily re-elected in 2006 after a sympathetic Congress amended the constitution to let him run for a second term.

But the constitution only allows for one re-election, so to run again the popular Uribe had to secure another constitutional amendment.

Uribe, speaking from the Caribbean port of Barranquilla, said that he will "obey and respect" the ruling.

"I hope to continue serving Colombia... to the last day of my existence," he said, adding that he trusts the next president "will maintain the levels of security and trust that we have recovered."

In his ruling, Gonzalez said the law calling for such a referendum included "substantial violations to the democratic principle."

"It is not a matter of mere... irregularities," he added.

Seven of the nine Constitutional Court justices voted against the measure, while two abstained, Gonzalez said.

The no-nonsense Uribe, 57, is credited with a successful law-and-order program and has an approval rating near 70 percent. More than 80 percent of Colombians said in a December poll that they would have supported Uribe if he was able to run for a third term.

The first round of voting in Colombia's presidential election is set for May 30.

Uribe, an attorney and supporter of free-market policies, is popular largely thanks to his US-backed campaign against the leftist Revolutionary Armed Forces of Colombia (FARC) guerrillas and for helping usher the country towards its best economic performances in 30 years.

The FARC, Latin America's oldest and largest insurgency, has been battling the Colombian government for four decades.

Uribe opponents say the military's success has been accompanied by a rise in human rights violations and that the president's economic strategy only benefits big business.