British Foreign Secretary David Lammy and US Secretary of State Antony Blinken, who will jointly visit Kyiv this week, said on Tuesday they are united on the need to tackle Iran's influence in the Middle East and Ukraine.

"(We are) completely aligned on the need to tackle Iran's malign activity in the region and beyond," Lammy told reporters beside Blinken, who is visiting Britain.

"We're seeing a disturbing pattern of greater Iranian support for the Kremlin's illegal group, and we discussed today our shared commitment to holding Tehran to account for their undermining of global stability."

Blinken said Iran's decision to supply Russia with ballistic missiles threatened European security and he announced further sanctions on Tehran.

"Russia has now received shipments with these ballistic missiles, and will likely use them within weeks in Ukraine, against Ukraine," Blinken said, citing intelligence that he said has been shared with US allies and partners around the world.

The supply of Iranian missiles enables Russia to use more of its arsenal for targets that are further from the front line in Ukraine, Blinken said.

"This development and the growing cooperation between Russia and Iran threatens European security and demonstrates how Iran's destabilizing influence reaches far beyond the Middle East."

Lammy said he and Blinken would travel to Kyiv this week, the first joint visit of this kind for more than a decade.

The British foreign minister described the supply of ballistic missiles from Iran to Russia on Tuesday as a "significant escalation".

"This is a troubling action that we're seeing from Iran. It is definitely a significant escalation and we are coordinating," he said.

Lammy said he would not comment on "operational issues" when asked whether Britain would give the green light to Ukraine to use the Storm Shadow long-range missiles to strike targets inside Russia.

(Report by Reuters)