EU countries are not stumping up the cash to help Turkey deal with the migration crisis, forcing the European Commission to increase its share of the €3 billion promised to Ankara, according to multiple diplomatic sources.

At a summit between EU leaders and Turkey at the end of November, the bloc agreed to provide “an initial €3 billion of additional resources” to Turkey in the fight against illegal migration. Of that figure, €500,000 was supposed to come from the Commission, with the rest from national governments.

But several countries have objected to this plan and asked the Commission to increase its stake.

Doubling the Commission’s financial commitment was discussed informally at a European Council in December and again at a meeting of EU ambassadors, but it is not on the agenda of Wednesday’s meeting of permanent representatives to the EU at which migration will be discussed, a diplomat said.

A Commission spokesman said “there is a feeling that we are getting closer to an agreement” on a new proposal for sharing out the financial commitment.

Diplomats disagree. “The new proposal is not officially on the table because many countries are still unhappy with the results on the agreement with Turkey that so far has not brought tangible results,” a national diplomat said. The money is supposed to help Turkey deal with the 2.2 million Syrian refugees on its soil and to stem the flow of migrants crossing to Europe. As well as the money, the EU promised fresh efforts in Turkey’s EU membership bid.

Other national officials said that Frans Timmermans, the Commission’s first vice president, has hardened his rhetoric on Turkey in recent days as a response to criticism of Turkey’s efforts on migration from member countries.

“We are all committed as part of the joint action plan to bring the figures [of refugees moving from Turkey to the EU] substantially down,” Timmermans said last week. But he also complained that “it’s quite clear that over the last couple of weeks the figures have remained relatively high.”

Turkey said it plans to offer Syrian refugees work permits, Volkan Bozkir, the European affairs minister, said on Monday after a meeting with Timmermans.

Were the Commission to increase its contribution to €1 billion it would not force cuts to other items such as agricultural or structural funds, said another diplomat, so the budget would remain unchanged.

In its original proposal the Commission put forward a criteria for national contributions, based on their gross national product. Germany would have paid the most €534 million, with France paying €386 million and Italy €281 million. The criteria will remain the same in any new proposal, a diplomat said.

Cyprus, the northern part of which is under Turkish control, does not have to contribute.

On Wednesday, Timmermans will brief the college of commissioners on his meetings with Turkish officials.