SANA'A: Yemeni President Ali Abdullah Saleh was slightly injured in a shelling attack on his palace Friday as fighting intensified in the capital of the impoverished country. Saleh, who is facing an unprecedented challenge to nearly 33 years of rule, said seven people were killed when a mosque in the presidential palace was shelled by his tribal foes. “I salute our armed forces and the security forces for standing up firmly to confront this challenge by an outlaw gang that has nothing to do with the so-called youth revolution,” said Saleh, speaking only via audio in a televised speech. An official earlier said Saleh, 69, suffered minor injuries in the attack but was in “good health”. A senior diplomat said the prime minister, his deputy, the parliament speaker and other aides were among the injured. Global powers are worried that Yemen, home to a wing of militant group Al-Qaeda known as AQAP, could become a failed state raising risks for world oil supplies. Yemen has tipped swiftly toward civil war this week, with Hashed tribesmen battling Saleh forces in Sana'a. More than 370 people have been killed, at least 155 of them in the last 10 days, since a popular uprising began in January against Saleh's long rule. On Friday, fierce fighting engulfed the capital, where residents cowered in their homes as explosions rocked the city. “A cowardly attack with an explosive projectile took place during Friday prayers at the presidential palace mosque where ... Saleh and senior government officials were present,” state news agency Saba said. The government blamed the shelling on Hashed tribesmen led by Sadeq Al-Ahmar, whose family has backed those demanding Saleh's overthrow. Ahmar later denied responsibility and accused Saleh himself of orchestrating the attack to justify a government escalation of street fighting in the capital. Suspicion has also fallen on breakaway General Ali Mohsen, who defected to the opposition in April and sent his troops to Sana'a to protect anti-Saleh demonstrators. Forces loyal to Saleh later shelled the homes of the leaders of the Hashed tribe, sources said. The US condemned the escalating violence and called for an orderly and peaceful transfer of power. EU foreign affairs chief Catherine Ashton deplored the loss of life and said the European Union would help EU citizens wishing to leave Yemen. “I have repeatedly urged President Saleh to listen to the demands of the Yemeni people and transfer power,” she added.