US President Joe Biden has ruled out sending F-16 fighter jets to Ukraine, despite renewed calls from Ukrainian officials for urgent air support.

Asked by a reporter on Monday if the US would be providing the planes, Mr Biden simply replied "no".

His comment comes a day after Germany's leader also ruled out sending jets.

Ukraine has long been pushing its allies to send advanced war planes to help Kyiv take control of its airspace in its ongoing war with Russia.

Ukrainian President Volodymyr Zelensky and the country's top military officials say there should be no taboos on such military aid - but the US and its partners fear this would lead to further escalation with a nuclear-armed Russia.

US-made F-16 Fighting Falcons are widely considered one of the world's most reliable fighter jets and are used by other countries, such as Belgium and Pakistan.

They would be a significant upgrade on the Soviet-era fighting jets - mostly MiGs - Ukraine is currently using, which were made before the country declared independence from the USSR in 1991.

However, Mr Biden has repeatedly rebuffed Ukraine's pleas for the jets, instead focussing on providing military support in other areas.

The US announced last week it would supply Kyiv with 31 Abrams tanks, reversing its earlier stance on the issue. The UK and Germany also pledged similar support.

Ukrainian Deputy Foreign Minister Andriy Melnyk welcomed that announcement but asked allies for the creation of a "fighter jet coalition" that would also provide Ukraine with Eurofighters, Tornados, French Rafales and Swedish Gripen jets.

In an interview on Sunday, Germany's chancellor said that it "seemed frivolous" to discuss sending other military aid to Ukraine when his government had just committed to sending Leopard 2 tanks.

Olaf Scholz also reiterated to German newspaper Tagesspiegel that the Nato military alliance was not at war with Russia and that it would "not allow such an escalation".

Meanwhile, French President Emmanuel Macon said on Monday that "by definition, nothing is excluded", referring to military assistance to Ukraine. But he stressed that it must neither further inflame the situation nor limit France's ability to defend itself.

Ukrainian Defence Minister Oleksii Reznikov is now in Paris, where he is expected to discuss the issue with top French officials.

Poland - another key ally of Ukraine - has also not ruled out sending F-16s to Kyiv. However, Polish Prime Minister Mateusz Morawiecki said any such move would only be possible "in complete co-ordination" with other Nato members.

Andriy Yermak, the head of President Zelensky's office, said that Ukraine had received "positive signals" from Warsaw.

Moscow has repeatedly accused Nato of being an aggressor by proxy and members of the alliance, including the US and Germany, have been reluctant to send military aid that could see the conflict escalate.