A senior police officer who played a key role in the investigation into the slaying of a former Lebanese prime minister was wounded in a bomb attack today in which four of his bodyguards were killed.

Lieutenant-Colonel Samir Shehade was involved in the arrest last August of four pro-Syrian generals accused of involvement in the February 2005 assassination of the former premier Rafik Hariri, who was killed in a massive car bomb.

Today's bomb attack comes 10 days before Serge Brammertz, the UN chief investigator, is due to submit a report to the Security Council updating his findings on the Hariri investigation.

Colonel Shehade was targeted by a remote-controlled bomb that was set off as his two-vehicle convoy passed through the village of Rmaile, near the southern port city of Sidon.

Ahmed Fatfat, the Interior Minister, told the Lebanese Broadcasting Corporation that the blast was caused by a roadside bomb loaded with nails. He said that it targeted the car normally driven by Colonel Shehade, who was traveling in the other vehicle at the time.

Mr Fatfat did not say who might have been behind the attack but said it could have been aimed at Lebanese security forces, who are deploying to south Lebanon under a UN-brokered cease-fire deal that ended a month of fighting between Israel and Hezbollah guerrillas.

Lebanese army troops are supposed to deploy in the south with a beefed-up UN peacekeeping force as Israeli troops withdraw.

The roadside bomb was detonated by remote control as the convoy travelled along a major road between two bridge, security officials said. Two of his bodyguards were killed in the explosion and two others died of their wounds at hospital.

Colonel Shehade was taken to Sidon's Hammoud hospital, where his condition was described as stable.

Previous reports have implicated top Syrian and Lebanese security officials in the Hariri killing, which rocked Lebanese politics and led to the withdrawal of Syrian troops from Lebanon, ending a 29-year-military presence. Syria denies any role in the Hariri slaying or the subsequent bombings.

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