After 18 days in captivity 70-year-old businessman Kiro Kirov was set free by his kidnappers late on April 13 2009, Interior Ministry said.

"At 10.30pm Kirov contacted his family after he was released by his kidnappers," a statement on the ministry's website said. He is currently in the family house in Sofia's Bozhourishte borough. He was examined by a doctor who confirmed that Kirov was in a good condition, the statement said.

"The Interior Ministry and the General-Prosecutor's Office are continuing to try to find Kirov's kidnapper," the statement also read.

Kirov's son Ivan told private national bTV channel that his father called him at about 11pm on April 13 2009 and said that he was in Gorna Banya borough.

Kirov was set free almost two days after his son said he had left a bag with 620 000 euro under a bridge on Trakiya highway near Sofia on April 11 2009.

According to media speculation, Kirov's son received several orders from kidnappers to change the place of the drop because they could see that he was being followed by the police.

Allegedly, the kidnappers retrieved the money with a hook and disappeared into the night driving a 4x4 BMW with police failing to make an arrest. Interior Minister Mihail Mikov refused to comment on whether police knew about the ransom paid to the kidnappers.

On April 13 2009, however, Ivan Kirov told reporters that he had fulfilled his part of the deal and asked kidnappers to do the same and release his father which they did a few hours later.

Allegedly, they first demanded three million leva but later agreed on one million leva, roughly the equivalent of 620 000 euro.

Kirov is the founder and owner of Kirov PLC, one of the largest companies dealing with the import and sale of earthmoving and construction equipment.