Ukrainian President Volodymyr Zelenskyy traveled to two European capitals on Wednesday in search of better aerial firepower to turn the war against Russia, winning a British pledge to train Ukrainian pilots on advanced NATO fighter jets.

On just his second trip abroad since the war began a year ago, Zelenskyy met British Prime Minister Rishi Sunak and King Charles in London before flying to France.

In Paris, the Ukrainian president met French President Emmanuel Macron and German Chancellor Olaf Scholz. Both vowed continued support for Ukraine ahead of a discussion on Wednesday evening about Kyiv's wartime needs.

"We have very little time. I'm talking now about the weapons needed for peace and to stop the war started by Russia," Zelenskyy said.

"France and Germany have the potential to be game changers and that's how I see our talks today. The sooner we get heavy long range weapons and our pilots get modern planes ... the quicker this Russian aggression will end."

In a speech to British lawmakers, Zelenskyy similarly stressed his plea for combat aircraft, which he referred to as "wings for freedom". Western countries have so far stopped short of providing planes or weapons that can strike deep inside Russia.

At a joint news conference with Zelenskiy later in the day, Sunak said "nothing is off the table" when it comes to supplying Ukraine with jets to fight Russia.

"The first step in being able to provide advanced aircrafts is to have soldiers or aviators that are capable of using them. That is a process that takes some time. We've started that process today," Sunak said.

Russia's embassy to Britain warned London against sending fighter jets to Ukraine, saying such a move would have ramifications for the entire world, TASS news agency reported.

Britain announced plans to expand a program training Ukraine's military to ensure its pilots could fly sophisticated jets of NATO military alliance standard.

The announcement gave no timeframe and did not commit to provide Kyiv with British jets. But it signalled a shift that could pave the way for other nations to send planes.

Zelenskyy's tour of Europe, which will also include a European Union summit in Brussels on Thursday, follows a surprise visit to Washington in December.

Britain announced the addition of new names to its Russia sanctions blacklist, as well as plans for more military equipment for Kyiv, including unspecified longer range weapons.

As Zelenskyy wrapped up his London speech, air raid sirens rang out in Ukraine's capital Kyiv. An all-clear later sounded.

Germany's Scholz told the lower house of parliament in Berlin before traveling to Paris he expected strong support for Ukraine from this week's EU summit and a new round of European sanctions on Russia around the anniversary of the invasion on Feb 24.

His defense minister said Western allies could deliver a first battalion of about 31 Leopard 2 battle tanks to Ukraine in the early months of this year.

After major Ukrainian gains in the second half of 2022, Russia has recovered momentum, sending tens of thousands of freshly mobilized troops to the front. They have made incremental progress in relentless winter battles which both sides describe as some of the bloodiest fighting of the war.

Kyiv says it expects Moscow to broaden that offensive with a big push as the Feb. 24 anniversary of the invasion approaches.

Russia launched its "special military operation" last year to combat what it describes as a security threat from Ukraine's ties to the West, and claims to have annexed four Ukrainian provinces. It says Western military aid will prolong the war.

Western fighter jets are at the top of Ukraine's wish list. U.S. President Joe Biden said last month Washington would not send U.S. F-16s to Ukraine, and British officials have said their jets require too much training to be useful now. France and Poland are among countries that have kept the door open to sending jets as part of a collective Western decision.

The United States is expected to announce a $2 billion weapons package in coming days that would include new rockets with bombs that double the range of rockets it sent last year. That would put all of Russia's supply lines in mainland Ukraine as well as parts of the Russian-annexed Crimean peninsula within firing distance.