Russian President Vladimir Putin has expressed deep condolences to UK Prime Minister Theresa May over the deadly terror attack at the Manchester Arena in England, the Kremlin press service said on Tuesday, TASS reports.

"We strongly condemn this cynical and inhuman crime. We expect that its masterminds won’t go unpunished," the Russian president stressed in a telegram.

Putin "confirmed readiness to step up anti-terrorist cooperation with British partners - both on bilateral basis and as part of broad international efforts."

The president conveyed the words of sympathy and support for the families of those killed and wished a speedy recovery to all those injured.

The blast occurred at the Manchester Arena at 10.35 p.m. local time on Monday shortly after a concert of US pop singer Ariana Grande. An explosive device went off outside the concert hall. Police are treating the incident as a terror attack.

According to the latest data, 22 people, including children, were killed and another 59 people were wounded.