An American man says he was denied entry to Canada at Vancouver's airport because of a conviction stemming from a high school prank 20 years ago.

San Francisco resident Jon Cobb, who says he has visited Canada four or five times before, flew to Vancouver on Saturday planning to see friends for a few weeks. Instead, he was sent home the same day after at least seven hours of questioning.

"I was basically flabbergasted, trying to figure out what these questions have to do with visiting friends in Canada."

Cobb said border officials questioned him about his uncle's death in a bus accident in 2009, scrutinized his belongings, took his cellphone and read his text messages.

Finally, he said, the real problem was revealed — a burglary conviction resulting from a high school prank more than 20 years ago.

"I told [the agent], I said it was prank week in high school and we broke into a rival school to steal the mascot — it was a goat."

Cobb was denied entry into Canada even though he had visited previously with little problem.

"I've been to Vancouver four or five times," he said. "I've always had this extra screening, every single time, and this time was the most brutal. It was quite possibly the most humiliating experience I've ever had in my life, being escorted all around the airport and people looking at me like, 'What did that guy do?'"

Databases going 'deeper and deeper'

Cobb's story comes after members of Tinariwen —  a musical group from Mali headed to Vancouver to play the annual folk festival —  were denied entry on Friday.

It appears the group was turned away because some members had been involved in a civil war in their native country, even though the band had played in Vancouver during the 2010 Winter Olympics.

Vancouver Centre Liberal MP Hedy Fry can't speak to either case specifically, but said she has heard other complaints from people frustrated with what seem like new roadblocks at Canada's borders.

"There are rules and there is an inconsistency with how those rules have suddenly been applied starting this year."

Meanwhile, one Vancouver immigration lawyer said he's not surprised to hear people are being denied entry to Canada for apparently minor convictions.

Zool Suleman said the clampdown that began after the Sept. 11 attacks has become even more restrictive in the last few years.

"The databases for criminal conduct are going deeper and deeper, so the short answer is, no, this does not surprise me at all," Suleman said.

"I am hearing of convictions that are 30 years old —  municipal type of convictions, driving convictions —  where the individual thought things had been taken care of a long time ago."

The Canada Border Services Agency said decisions are made on a "case by case" basis and even misdemeanours can mean entry is denied.