A British man has been charged with terror offences after he allegedly threatened to blow up the offices of the US state department.

The 28-year-old is accused of making two posts to Twitter in the hours after the November attack on the US diplomatic compound in Benghazi.

His posts contained threats of “shooting up” US embassies in the Middle East and other countries, the FBI said in a statement on Wednesday.

In one of the posts, the man said he wanted to kill a US ambassador and a US diplomat in Saudi Arabia.

The FBI said he also posted a threat to kill the head of the State Department’s Bureau of Democracy, Human Rights and Labor.

A spokesman for the FBI in New York declined to comment.

The US Embassy in Britain said it was “aware of reports of an allegation of a threat against the US embassy in the UK”.

The US Department of Homeland Security and the State Police are investigating.

The man’s family has not commented.

The incident happened at the height of tensions between the two countries, with tensions between Washington and London over the ongoing investigation into the attack.

Earlier this month, the UK’s prime minister, Theresa May, said her government would “stand shoulder to shoulder” with Washington to “put an end to the violence”.

“There are still hundreds of British nationals overseas who are facing significant security risks from the Islamic State,” she said.

“We will continue to do all we can to ensure they are safe.”

She said there was a “growing need for the UK to stand shoulder to knee with the US and to put an end” to terrorism.