Ukrainian President Volodymyr Zelenskyy says his request for combat aircraft is being considered following a meeting with European Union leaders in Brussels, where he also renewed calls for Ukraine to join the bloc.

Emerging from the meeting, Mr Zelenskyy told reporters that several EU leaders were ready to provide Kyiv with aircraft to help it fight against Russia's invasion.

After visiting London and Paris the day prior, Mr Zelenskyy said he also had "certain agreements, which are not public but positive", without elaborating.

Dutch Prime Minister Mark Rutte urged caution to his neighbours, voicing concerns over drawing Russia into direct conflict with the West.

"These type of decisions, you have to take behind closed doors. Because there are many sensitive issues to be discussed, the pros and cons .... You have to make absolutely sure that you are not getting into an Article 5 direct confrontation between NATO and Russia," Mr Rutte told the BBC.

Article 5 refers to NATO's founding treaty, which compels all allied countries to defend a member state if it is attacked.

Ukraine is not a member of NATO, but any backlash from Russia against one supporting Ukraine would likely draw the alliance into the conflict.

British Prime Minister Rishi Sunak had promised to train Ukrainian pilots to fly advanced NATO fighter jets, although he stopped short of offering to supply the planes, an indication an offer from another ally was on the horizon.

UK Defence Secretary Ben Wallace told BBC reporters there were no immediate plans for the UK to send jets to Ukraine, and labelled calls for the transfer of the country's Typhoon warplanes "unrealistic".

Only two weeks ago, Germany and the US  pledged to donate some of their powerful tanks to bolster Ukraine's military.

Mr Zelenskyy had arrived at the European Parliament to rapturous applause, insisting in his speech that Ukraine's fight against Russia was one fought for the freedom of Europe as a whole, referring to Russia as "the biggest anti-European force of the modern world."

"I am grateful to all of you who are helping, grateful to everyone who understands how much Ukraine right now needs these possibilities. We need artillery guns, shells for them, modern tanks, long-range missiles, modern aircraft," he said.

The EU said it would announce further sanctions against Russia, including new export bans and the targeting of propagandists for Russian President Vladimir Putin.

"We will target Putin's propagandists because their lies are poisoning the public space in Russia and abroad", European Commission President Ursula von der Leyen said.

The new sanctions "will further starve Russia's military machine and shake the foundations of its economy", she added.

In addition to Mr Zelenskyy's request for greater military support and added sanctions on Russia, he hoped to increase pressure to fast track Ukraine's membership to the EU.

Ms von der Leyen said that Ukraine was making "impressive" progress on the path to European integration, but stressed there is "no rigid timeline" on the process.

"The Commission is working very closely with the Ukrainian government … there is no rigid timeline, it is a merit-based process."

Ukraine's entry into EU is a complex matter

The EU granted Ukraine candidate status last June, but it traditionally takes many years to be fully accepted into the bloc.

Croatia, for example, is the most recent country to join the bloc and was welcomed in almost a decade after receiving candidate status.

The delay speaks to the EU's strict requirements for member states to be considered fit to join, including conforming with a host of standards ranging from judicial policy to financial services, food safety and corruption.

European officials have said that Ukraine has already adopted about 70 per cent of the EU rules and standards, but they also have pointed to issues with corruption and the need for deep political and economic reforms in the country.

Mr Zelenskyy says he has already begun weeding out internal corruption, pointing to the recent outsings of several Ukrainian senior officials, including the deputy minister of infrastructure, as part of anti-corruption investigations.

The Ukrainian President has been vocal in his desire for Ukraine to join the EU within two years, but the country's fate balances on far more complex issues.

The EU, once a collective of just six allied countries, has struggled against internal divisions following a rapid expansion in the 21st century.

The EU is bound by a unanimity rule, which means every country must agree before the bloc can pass a law on a range of issues from foreign policy to tax rules. With 27 nations in the bloc, drafting a proposal that meets the expectations of all can be painstaking.

Influential members France and Germany have argued the EU needs to reform the way it works before entering any more members, including Ukraine.

Fast-tracking Ukraine's membership also risks fallout from a show of preferential treatment.

Some candidate countries joined the queue long before Ukraine. Turkey, for example, has been a candidate since 1999, after first applying in 1987.

Following Mr Zelenskyy's Brussels address, European Council chief Charles Michel hinted at a lengthy process for Ukraine's admission.

"The road to peace, reconstruction and membership will be a long, hard road," Mr Michael said.

"We'll be with you every step of the way," he added.

ABC with wires