An Irish civil engineer was killed Tuesday by at least one gunman who burst into his office in the Saudi capital, officials said.

It was not clear if the shooting was linked to a wave of anti-Western attacks in the country, the world's largest oil exporter, by supporters of the al Qaeda network headed by Saudi-born Osama bin Laden.

"We can confirm that an Irishman was killed in Riyadh," said an Irish Foreign Ministry spokeswoman in Dublin. "Our consular section and our embassy in Riyadh are involved. Beyond that, we're not in a position to comment further."

A security source identified the victim as Tony Christopher, 63, and said he was a civil engineer working for a Saudi company. "He was shot twice and the gunman might have used a silencer, since no one in the office next door heard anything," the source said.

A Western diplomat said there was no immediate information on any motive, and a statement by the head of the Riyadh police said the shooting was being investigated.

Militants linked to al Qaeda have targeted Western nationals since May 2003 in a campaign to destabilize Saudi Arabia. They have also attacked government institutions and oil industry areas. About 90 policemen and civilians, many of them foreigners, have been killed.

In June, Saudi gunmen killed an Irish cameraman working for the BBC and wounded his British colleague as they filmed in an area of Riyadh populated by Islamic militants.

Saudi Arabia has said militants were going after individuals and soft targets because of a tough security clampdown over the past year.

Saudi forces killed the local al Qaeda leader, Abdulaziz Muqrin, and three others after they beheaded an American hostage, Paul Johnson.

Ireland has advised its citizens against nonessential travel to Saudi Arabia, and its embassy has urged Irish residents to take security measures.