PARIS (Reuters) - Former France defender Lilian Thuram said on Friday he could not sign a deal with Paris St Germain because of a heart problem.

Thuram told a news conference the problem had been spotted during a medical examination after which he had been expecting to join PSG from Barcelona on a one-year deal.

"I am sadly not holding this news conference to tell you that I'm joining PSG but to tell you that the doctors have detected a heart malformation," he said.

"It's a total surprise, I didn't see it coming," added Thuram, who will undergo further tests to determine how serious the problem is.

"In a month or so I should know whether I can pursue my career or if I have to stop," he said.

Thuram said the problem, believed to be a heart hypertrophy, could be the same as the condition suffered by one of his brothers, Antonio, who died of a heart attack while playing basketball in the 1990s.

"It seems to be the same illness as my brother," Thuram said, adding that other members of his family suffered from heart problems.

PSG coach Paul Le Guen said he hoped Thuram would eventually be able to join the capital club.

"I still hope he will be able to help us out," Le Guen told reporters.

The 36-year-old Thuram, a member of France's 1998 World Cup-winning team, won a record 142 caps for his country. He announced his international retirement after France's group-stage exit from Euro 2008.

One of the most popular French players, Thuram helped the side to win the 2000 European Championship and reach the final of the 2006 World Cup. He played for Monaco, Parma and Juventus before joining Barcelona in 2006.

(Writing by Patrick Vignal, editing by Clare Fallon)