AL QUDS, March 7: An official investigation is to be held into how Israeli Prime Minister Ariel Sharon came to approve a controversial prisoner exchange deal with Hezbollah, State Comptroller Eliezer Goldberg said on Sunday.

Goldberg "has decided to investigate the process by which the decision to approve the prisoner exchange deal with Hezbollah, in which Elhanan Tannenbaum was returned to Israel, was made," a statement from his office said.

"The state comptroller will decide on the scope of the investigation during the inquiry." There has been increasing public disquiet over the deal that went through in late January, which reached new heights last week when it emerged that Sharon had a business relationship with Tannenbaum's father-in-law. Tannenbaum was captured by the Hezbollah men in Dubai in October 2000 while reportedly travelling to the Gulf to conduct a drugs deal.

He was held in Lebanon until he was repatriated along with the bodies of three Israeli soldiers in exchange for the release of more than 400 Arab prisoners.

Tannenbaum has been kept in custody for interrogation since then but a backlash has been brewing as details of the 57-year-old reservist colonel's background and private life have come to dominate the front pages.

Sharon says that he has no regrets about the deal, insisting that he was completely unaware that Tannenbaum was related to his one-time farm manager Shimon Cohen.

The premier's approval ratings have plummeted, with many observers arguing that Sharon deliberately decided not to reveal his relations with the Tannenbaum family during a cabinet meeting last year in which the ministers agreed to the exchange by a single-vote majority. The state comptroller is Israel's main public watchdog but any reports that he issues are merely advisory.

Opposition deputies had been pushing for a parliamentary inquiry to be carried out by the influential defence and foreign affairs committee but such a probe now appears unlikely.

Labour deputy Ophir Pines told army radio that the state comptroller was the only person capable of carrying out an objective investigation into the affair. Minister without portfolio Uzi Landau, who is seen as close to Sharon, said that such an inquiry should draw a line under the whole affair.

Observers have warned that the haemorraging of trust in Sharon, who is at the centre of two corruption scandals, threatens to hamstring his programme to pull out of most of the Gaza Strip.

"In this mounting paranoia there is at least one new element that must be of profound concern to the prime minister: the lack of trust in him that is shared by all the political camps," an editorial in Sunday's top-selling Yediot Aharonot said.

"Even the proponents of a withdrawal from Gaza will find it hard to support a prime minister who placed his full weight behind the release of Tannenbaum for concealed reasons, and without having shown the necessary leadership when it became evident that the entire deal proved to be complete chaos."

Meanwhile, magistrates at a court near Tel Aviv granted the security services on Sunday an extra 10 days in which to detain Tannebaum for questioning, judicial sources said. -AFP