Right-wing Colombian paramilitaries have freed one of Venezuela's richest men after holding him hostage for exactly two years.

The businessman, Richard Boulton, was handed over to the International Red Cross in central Colombia on Monday.

To Carlos Castano I'm highly grateful

Alberto Boulton, kidnap victim's brother

It comes days after the leader of the outlawed United Self-Defense Forces of Colombia (AUC) resigned after acknowledging his group had seized Mr Boulton.

Mr Boulton's brother, Alberto, told Venezuelan television that he had passed ransom money to Venezuelan military intelligence in February to secure Richard's release.

Colombia has the highest kidnapping rate in the world, with more than 3,000 people taken hostage last year alone.

Kidnapped from home

Mr Boulton, 37, was snatched in a commando-style raid on his home in Tocuyito, Venezuela, on 15 July, 2000.

His kidnappers flew him away in his own plane, while other gang members escaped in cars.

Until last week it was unknown who was behind the kidnapping.

At first, the Venezuelan Government blamed Colombia's left-wing paramilitaries, who have been responsible for most of Colombia's hostage-taking cases.

But on Friday, Carlos Castano, the political leader of the AUC, said the group was holding Mr Boulton.

Leader's 'disgust'

Mr Castano said he had been unaware of the AUC's involvement in the kidnapping and told the group to free Mr Boulton when he found out.

Castano resigned in protest at the kidnapping

He said he was so disgusted by the AUC's actions that he was resigning from his position in protest.

Mr Castano made a similar offer to quit last year, in a move widely seen as aimed at gaining political respectability for the paramilitary group, which has been responsible for many of Colombia's worst human rights abuses.

Alberto Boulton paid tribute to Mr Castano role's in freeing his brother.

"I think that Carlos Castano was the key person in Richard Boulton's release... to Carlos Castano I'm highly grateful," he said.

Ransom paid

The Venezuelan Government said it was involved in efforts to secure Mr Boulton's release.

But Alberto Boulton said he was puzzled why his brother was not freed sooner.

"To me it seems strange that after having paid the ransom, which I personally handed over on 5 February, so much time has passed without even a proof of life, or knowing his physical condition or any type of contact," he said.

The Red Cross said Mr Boulton was freed in the province of Meta and had been joined by members of his family.

Officials refused to discuss the circumstances of his release or what condition he was in.