He did not give a figure, but the EU has already sent 2.5 billion euros ($2.5 billion) in total to Ukraine and his office indicated it would be of the same magnitude as the five previous tranches, each 500 million euros.

"We'll be putting some concrete requests on the table soon. We're going to move up to the sixth military assistance tranche coming up via the European Peace Facility," Josep Borrell told the European Parliament.

Ukraine uses the money to pay for weapons as it fights a Russian invasion. NATO countries have also supplied material from their arsenals.

In recent days, Ukrainian forces armed with sophisticated Western rockets and artillery sent Russian troops into hasty retreat in an eastern region of the country.

The EU in addition has agreed to provide nine billion euros in non-military funding to Ukraine. One billion of that has already been given, with another five billion euros authorised.

Borrell said the outstanding three billion euros depended on member states giving assent.

"No doubt a lot more must be done. But that's what international financial institutions are there for, not just the European Union," he said, noting that Kyiv was holding talks with the International Monetary Fund.