SANA'A ��" Yemen has boosted security at energy installations to guard against militant attacks, a government official said on Sunday, as Sanaa escalated its war against al-Qaeda. Yemen, a small oil producer with output of around 300,000 barrels per day, has come under pressure to act against al-Qaeda since attacks on its two main allies, Saudi Arabia and the United States, by militants coming from Yemeni soil. "The security measures have been strengthened for some time. But we took additional measures around oil institutions and the gas project in Shabwa," the official told Reuters, adding the measures were put in place "in case of any terrorist attacks." Other officials said fresh measures included sending extra security forces and police to guard oil and gas facilities. They said the measures were implemented on Saturday, a day after Yemen said an air strike killed six al-Qaeda militants. Yemen gained a reputation as a haven for al-Qaeda after the September 11, 2001 attacks in the United States, and came under the spotlight after crackdowns on the group in Pakistan and Afghanistan raised concerns it was becoming a training and recruiting center for militants. The Yemen wing of the global militant network, al-Qaeda in the Arabian Peninsula, has strongholds in Yemen's eastern province of Hadramaut and the towns of Maarib and Shabwa, where oil and gas fields of major international companies are located. Yemen is an oil producing minnow in a region of export giants such as neighbor and top exporter Saudi Arabia, so interruption of its oil output would have little impact on international energy markets.