The European Union is to add 2 billion euros ($2.1 billion) to a fund used to help arm Ukraine, as paying for weapon deliveries has drained the coffers, European diplomats said Friday.

Diplomats said a preliminary agreement had been struck among the 27-member bloc to bolster the European Peace Facility, which has already committed over 3 billion euros to covering the cost of weaponry for Kyiv.

It was hoped that foreign ministers meeting in Brussels on Monday would formally sign off on the move.

But diplomats said a separate standoff with Hungary over its own frozen EU funds could see Budapest delay approval.

The European Peace Facility was set up last year to help the European Union fund military assistance to its international partners as the bloc looks to increase its global clout.

Russia's invasion of Ukraine in February saw the vast bulk of the fund diverted to help arming Ukraine as Brussels broke a long-standing taboo on not paying for arms deliveries.

Only 800 million of the facility's original budget of 5.7 billion euros to 2027 now remains.

Officials are keen to boost it to ensure the bloc can commit to further helping Ukraine next year as the war drags on.

The fund is used to reimburse arms supplies by individual member states to Kyiv.

So far, together with its member states, the European Union has committed about 8 billion euros to military support to Ukraine, which is about 45 percent of the amount the United States has given.