The transfer of Iranian ballistic missiles to Russia represents a further military escalation and will be met with a "strong response" from the European Union, EU foreign affairs spokesperson Peter Stano said on Tuesday.

Stano said the EU's diplomatic service, at the request of foreign policy chief Josep Borrell, had already presented EU members with "a substantial set of decisive and targeted measures" against Iran in response to the transfer.

Any such measures would have to be agreed by all of the EU's 27 members to take effect, Stano added.

"We confirm (we) have received credible information about the delivery of Iranian ballistic missiles to Russia," he said.

"High Representative Borrell, in his bilateral contacts with the Iranian partners, has constantly warned Iran against such a decision," Stano said.

He said the transfer contravened the U.N. Charter, international law and international humanitarian law.

"A delivery of ballistic missiles will likely assist Russia’s escalatory bombing campaign against Ukrainian civilians, cities and civilian infrastructure, further increasing civilian casualties and destruction," Stano said.

"Such support to Russia’s terrorising campaign against Ukraine’s population will be met with a strong EU response."