Officials said Al Qaida has been targeting foreign oil workers in Yemen. They said Al Qaida operatives were arrested in connection with a recent attack.

At least two of the Al Qaida detainees were said to have confessed to an attack on an oil pipeline on June 19 near Aden, Middle East Newsline reported. Officials said the attack, designed to blow up the facility with TNT, was unsuccessful.

On Saturday, a Yemeni soldier opened fire on foreign oil staffers. At least two people were killed and five others injured at a facility of Occidental Petroleum Corp., which contains a significant presence in Yemen.

Shabwa Gov. Ali Al Maqdishi confirmed the shooting. Al Maqdishi said the soldier was deemed mentally ill.

This was the second Yemeni attack on foreign energy workers in three months. In March 2007, Yemeni workers assaulted Western staffers and torched vehicles and a helicopter at the construction site of a liquefied natural gas terminal. The riot was sparked by rumors that a French national had thrown a copy of the Koran during an argument with a Yemenite colleague.

In response to Saturday's attack, the U.S. embassy in Sanaa canceled travel to the Shabwa and Marib provinces. The embassy urged Americans to stay away from the region.

"An attack on oil company personnel near the border between Marib and Shabwa governorates this morning has resulted in casualties, including one American citizen critically injured," the embassy said in a warden message on Saturday. "The U.S. embassy has cancelled all official and non-official travel by embassy personnel to Marib and Shabwa governorates for the near future. The embassy continues to recommend that American citizens avoid traveling to Marib and Shabwa, and remain vigilant throughout Yemen."