LONDON, April 9 (Reuters) - Britain is working with its allies to agree a joint response to a reported poison gas attack on a rebel-held town in Syria, Prime Minister Theresa May’s spokesman said on Monday.

He also said Britain was not involved in overnight air strikes on a Syrian air base. Russian and Syrian military have blamed those strikes on Israeli war planes.

“If there is clear verified evidence of the use of chemical weapons and a proposal for action where the UK would be useful, then we will look at the range of options,” the spokesman said.

In a separate statement, Britain’s Foreign Office said a full range of options should be on the table in response to the reported attack.

The Syrian opposition have blamed the suspected chemical attack that killed dozens of people on Saturday in the town of Douma on Syrian government forces. U.S. President Donald Trump has said there would be a “big price to pay”. (Reporting by William James, writing by Estelle Shirbon)