Kidnappers are demanding a ransom of $4.5 million US for the safe release of three Canadian brothers and their driver, who were abducted near their family home outside Caracas, Venezuela.

The boys -- 17-year-old John Bryan, 13-year-old Kevin, and 12-year-old Jason -- were seized on their way to school some 300 metres away from their home on Feb. 23, their aunt Rose Faddoul told CTV.ca on Friday from Windsor, Ont.

"They were abducted by what appeared to be police officers. We have witnesses to attest to that," Faddoul said.

"They said that when they overtook the vehicle, the vehicle was escorted by several police officers on motorcycles."

The boys' uncle, Mourice Faddoul, told CTV Newsnet that the family is especially worried about the middle child, Kevin, whom he described as having a physical disability.

"He is on medication. He gets daily treatments, and we're very, very concerned about his health right now," he said in an interview from Windsor. "We need these children back."

The family says the captors have contacted them several times to demand the ransom.

"They called around noon the day they took the boys, and have called about four times since, demanding the same amount of money. They won't negotiate a lesser amount," said Rose Faddoul.

"The amount they are asking for is just an absurd amount of money, he simply can't get his hands on that money," she said of her brother, who is a businessman in the South American country.

John Faddoul was born in Canada but emigrated to Venezuela nearly 25 years ago and married a woman from the country. His three sons, who were born in Venezuela, hold dual citizenship. In Canada, they reside in the town of LaSalle, located south of Windsor on the border of the Detroit River.

"(John) is devastated. He is trying to be strong so that he can think straight, but at the same time, he is frozen with fear for his children," Rose Faddoul said.

One of the kidnappers was identified as a former security guard who had been dismissed from his post at the station gatehouse that protected the upscale mountain community where the Faddouls lived.

Meanwhile, Mourice Faddoul is urging the Canadian government to get involved.

"We would like the Canadian government to put pressure on the Venezuelan government to demand and tell these kidnappers that they have three Canadian children that need to come back home," he told CTV.

Foreign Affairs Minister Peter MacKay confirmed Friday that Canada's Foreign Affairs Department has contacted Venezuelan authorities about the case.

"We have received very minimal information at this point that there are three children who have dual citizenship in Venezuela that have been abducted. We are awaiting further information," MacKay told reporters.

"Again we have voluntarily made contact and indicated that we will co-operate in every fashion, but we have not received much in the way of detailed information at this point."

The abductions highlight an apparent rise in kidnappings in the South American country.

In February, 2005, Venezuelan police stormed a mountain camp and rescued the mother of Detroit Tigers pitcher Ugueth Urbina from kidnappers who demanded $6 million in ransom, ending an ordeal that lasted more than five months.

The raid left at least one of the abductors dead, but 54-year-old Maura Villarreal was unharmed.

Experts say about three quarters of the world's kidnappings occur in Latin America, with the bulk in Colombia, Mexico, Argentina and Brazil.

According to Venezuelan police, the number of reported kidnappings in the country rose from 51 in 1995 to 201 in 2002, the last year for which official numbers were released.

It's believed that many kidnappings go unreported because families quietly pay the ransoms.