BEIRUT, April 8 (Reuters) - A Syrian air base targeted in a U.S. cruise missile attack is operating again, the governor of Syrias Homs province confirmed on Saturday.

The United States launched the missile strikes on Friday in response to a chemical attack that killed 90 people including 30 children. It says the Syrian government launched the attack from the Shayrat air base. Damascus has strongly denied carrying out the attack and says it does not use chemical weapons.

The Syrian army said on Friday the attack had caused extensive damage to the base, which the United States says it targeted with 59 Tomahawk cruise missiles.

The airport is operating as a first phase, Homs governor Talal Barazi told Reuters. Planes have taken off from it, he added, without saying when.

Asked if it was true that Syrian planes were now taking off from Shayrat or that the air base is operating, a Pentagon spokesman referred questions to the Syrian government.

The Syrian Observatory for Human Rights, a UK-based organization that reports on the war, said warplanes had taken off from the base on Friday and carried out air strikes on rebel-held areas in the eastern Homs countryside.

An activist with an opposition air raid warning service said however that the first flight from the base was on Saturday morning.

U.S. President Donald Trump suggested on Twitter that the runway itself had not been the target of the missile strikes.

The reason you dont generally hit runways is that they are easy and inexpensive to quickly fix (fill in and top)!, he said.

A senior military source in the alliance fighting in support of President Bashar al-Assad said the airbase had been mostly evacuated thanks to a warning from Russia, which has deployed its military to Syria in support of Assad.

The senior military source, a non-Syrian, said only a few out-of-service jets were destroyed.

The United States warned Russia ahead of the attack.

Assad is also backed in the war by Iran and the Lebanese group Hezbollah, and other Iranian-backed groups.

The Pentagon said the missiles targeted aircraft, hardened aircraft shelters, petroleum and logistical storage areas, ammunition supply bunkers, air defense systems, and radars.

(Reporting by Kinda Makieh in Damascus, Laila Bassan and Tom Perry in Beirut, Yeganeh Torbati in Washington; Writing by Tom Perry; Editing by Hugh Lawson)