Britain is expected to supply Storm Shadow missiles for use by Ukraine on targets inside Russia, now that the US president, Joe Biden, has agreed to do the same for the similar American long-range Atacms weapon.

Keir Starmer, the prime minister, said at the G20 summit that the UK recognised it needed to “double down” on its support for Ukraine, while diplomatic sources briefed they expected other European countries to follow the US lead.

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Russia, however, accused the west of escalation and said that Biden risked adding “fuel to the fire” in Ukraine, and while Donald Trump remained silent on the issue, his son Don Jr accused the military industrial complex of wanting to get “world war three going”.

Storm Shadow missiles have a range of about 250km (155 miles), similar to the US Atacms, and have in the past been given to Kyiv by the UK and France to strike targets inside Ukraine’s internationally recognised borders.

But the US retained an effective veto on their use because it supplies a guidance system and repeated lobbying by the UK had failed to shift the US position, which has only begun to soften after the election victory of Donald Trump earlier this month.

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Ukraine had also become increasingly exasperated with Britain on the issue of long-range missiles, complaining earlier this month that not only had there been no progress on their use inside Russia but that the UK had stopped supplying them at all.