A group of al-Qaida gunmen opened fire at the British embassy in the Yemeni capital of Sanaa late on Monday, a police official said. The official told Xinhua that the al-Qaida gunmen opened extensive fire at the main gate of the British embassy while they were onboard a vehicle that moved very fast in the main street in front of the embassy, located in the eastern edge of Sanaa. 'Back-up security forces were immediately rushed to the scene to help protecting the British embassy and its staff,' the official told Xinhua, but declined to give further information if there is any casualty. The splinters of a projectile fired by rocket-propelled grenade (RPG) were found inside the embassy as the group of gunmen managed to flee the scene after the attack, according to the official. The attack on the British embassy rose the deadly assaults by the resurgent al- Qaida regional arm in the Arabian Peninsula on highly-guarded Western and local targets to five attacks since last month. Earlier in the day, Yemen said its military forces killed late on Sunday three al-Qaida militants, one of them said to be a top leader, in clashes that also caused the death of six government troops in the country's southern province of Shabwa, according to the Defense Ministry. A provincial security official told Xinhua late Sunday that six Yemeni soldiers guarding an Austrian oil company were killed when a group of al-Qaida gunmen attempted to raid the Austrian oil company in Shabwa. 'The attack hurt no staff of the foreign oil company and caused no damage to the company,' said the official. Yemen, the ancestral homeland of al-Qaida network leader Osama bin Laden, has intensified security operations and air raids against terrorist groups, after the Yemen-based al-Qaida wing claimed responsibility for a failed Christmas Day attempt to blow up a U.S. passenger plane bound for Detroit last year. 