British PM to cut short G7 trip after Manchester attack

Britain is on its highest terror alert level following Monday's bombing, meaning another attack is thought imminent, and police are searching for the perpetrator's accomplices.

May will attend the first day on Friday of the Group of Seven meeting in Taormina on the island of Sicily, which is due to be attended by US President Donald Trump, but will miss the Saturday talks.

"Based on the fact that we have a threat level which is currently critical and the ongoing situation here, the prime minister currently plans a shortened programme at the G7 so she is likely to return on Friday evening," a senior government official said.

Before heading to Sicily, May is due to attend the NATO summit in Brussels on Thursday, where she will urge the other leaders of the military alliance to step up their efforts in tackling terror.

NATO is expected to join the US-led coalition against the Islamic State jihadist group, one of Trump's key demands, diplomatic sources in Brussels said.

At the summit, May will reiterate that Monday's attack was "a callous and cowardly act that was all the more sickening in the way it targeted innocent and defenceless children and young people", according to aides.

An eight-year-old girl was among the 22 murdered at the Manchester Arena.

The prime minister will say she is "grateful for the support and solidarity shown by all our NATO allies" and point to the bombing as an example of why the international community must do more to tackle terrorism.

"A strong, capable and united NATO is at the heart of the security of each and every one of our nations. Our unity in responding to common threats is our most potent weapon," she is expected to say.

"We must redouble our resolve to meet the threats to our shared society, whether from terrorism or from Russia."