EU member states on Wednesday agreed to add five billion euros ($5.5 billion) to a central fund to pay for weapons sent to Ukraine.

The move provides a welcome boost for Kyiv as support from its other major backer, the United States, wavers and its outgunned forces struggle to hold back Russia.

Belgium, which holds the EU's rotating presidency, said ambassadors from the bloc's 27 nations had agreed "in principle" on the plan to support arms supplies to Kyiv in 2024 with five billion euros.

In the wake of Moscow's 2022 invasion, the European Union for the first time agreed to fund weapons deliveries to a country at war.

Since then it has committed 6.1 billion euros from its central European Peace Facility mainly to reimburse part of the cost of arms sent by member states to Ukraine.

The push to bolster the EU fund by an extra five billion euros was delayed for months amid wrangling from Germany and France.

Berlin insisted its bilateral support for Ukraine should be offset against its contribution, and Paris demanded that only weapons produced in Europe should be reimbursed.

Diplomats said Germany, the largest contributor to the fund, had struck a compromise with Brussels to offset a percentage of its own bilateral support against the fund.

They said France was also satisfied by a commitment that countries would prioritise purchases from European defence firms, but could look outside the EU if certain ammunition or systems were not readily available.

Overall since the Kremlin unleashed its war, Brussels says around 28 billion euros have been spent from member states and EU coffers to support Ukraine's military.

Ukraine's Prime Minister Denys Shmygal welcomed the additional money.

"Thank you Josep Borrell for your unwavering support to Ukraine on the road to victory," he posted on X, referring to the EU's foreign affairs chief.

Struggle to boost output 

The announcement of the latest funds for Ukraine comes as Kyiv's forces are under pressure along the front line in the face of ammunition shortages.

The United States on Tuesday announced a fresh $300 million weapons package for Ukraine, but a further $60 billion in funding remains stalled by Republicans in Congress.

Warnings have grown in Europe that a failure to keep up support for Kyiv could see it ultimately defeated and that an emboldened Kremlin might then attack other countries.

The EU is pushing to bolster weapons and ammunition production by its defence industry, but two years into the war it is still struggling to ramp up output.

The bloc is set to fall well short on a promise it made a year ago to supply Ukraine with a million artillery shells by this month.

The Czech Republic has in the meantime spearheaded an 18-nation coalition to buy artillery shells from outside Europe and this month Prague said the first of 300,000 shells could reach Kyiv within weeks.

Meanwhile, Russia has stepped up its arms production by putting its economy on a war footing and has received major deliveries of weapons from Iran and North Korea.

EU leaders are set to discuss efforts to boost Europe's industry and support Ukraine at a summit in Brussels next week.