RIYADH, June 17: As a Friday deadline loomed, the operation to rescue the kidnapped American citizen, Paul Johnson, has been stepped up in Riyadh. Saudi police and security forces continued their search for militants who had given the authorities a deadline ending on Friday for his safe release.

The US FBI was reported to be working with the Saudi authorities in the ongoing investigations. A US official has hinted that authorities are making some progress in the case.

"The Saudi authorities have a lead and can count on the US to give them any assistance they request or need," Robert Keith, press attache for the US embassy told the press here.

Security forces reportedly searched some western and southern districts of the capital Riyadh on Wednesday, including the Suweidi area, a known stronghold for militants.

Security sources said no arrests has been made. Security forces withdrew from the neighbourhood after surrounding it for hours on Wednesday night and searching a home and a mosque, agencies quoting witnesses said.

Security officials have not commented on the operation. On Tuesday, Saudi forces arrested two militants north of Riyadh as they increased security in and around the city in the hunt for Johnson's kidnappers.

One Saudi daily said three suspects had been detained, but the report could not be confirmed. Meanwhile, the Saudi Arabian oil company, Aramco, is beefing up security for workers and families unnerved by a wave of deadly militant attacks on expatriate workers in the kingdom, an Aramco official said.