(UPI) - Yemen has stepped up security measures at its vital installations following threats by presumed al-Qaida operatives.

A Yemeni official, who spoke on condition of anonymity, told United Press International Friday that all security precautions have been taken at ports, airports and oil installations, especially at the site of a project for liquefied natural gas (LNG).

He said security was beefed up after a group calling itself al-Qaida Branch in Yemen claimed responsibility for attacking two oil installations last September which the Yemeni authorities said they had foiled.

"Al-Qaida's threats to attack vital centers in the country are just made for intimidation... This group has no effective presence in Yemen anymore and it has since been quiet," the official said.

He said security measures were also tightened at all government institutions as well as around foreign interests and Western embassies.

A private U.S. institution for financing foreign investments, OPIC, expressed in a recent report fears that the LNG project it is funding in Yemen could be a target for a terrorist attack on the model of the October 2000 attack on the USS Cole, which was hit by a booby-trapped boat in the port of Aden killing 17 American sailors.

A spokesman for the Yemeni gas company said "security is a primary concern at the LNG project site and a security plan was put in place in coordination with the Yemeni authorities to protect it."

The interior ministry in an earlier statement played down al-Qaida pledges to attack U.S. interests in Yemen, stressing that the government "will hit with an iron fist terrorist elements and abort their criminal plans."

The LNG project is jointly owned by the Yemeni government, French Total, U.S. Hunt and a South Korean oil company.