BRUSSELS — Belgian Prime Minister Bart De Wever on Thursday evening ratcheted up his objections to the European Commission’s plan to use some €140 billion of frozen Russian assets held in Brussels to bolster Ukraine — dashing EU hopes of a breakthrough on mobilizing the assets.

De Wever’s intervention — in a strongly-worded letter to European Commission President Ursula von der Leyen and seen by POLITICO — came only hours before the EU executive is expected to issue a proposal addressing Belgium’s concerns on using the funds.

The Commission is pushing for the 27 EU member countries to strike a deal at a European Council summit next month so that the billions of Russian reserves held in the Euroclear bank in Belgium can be freed up to support Kyiv with a reparations loan. De Wever is resisting the “fundamentally wrong” scheme over fears Belgium will be on the hook to repay the cash if Russia sues.

Hopes had grown in recent days that De Wever could reverse his position if the European Commission were to offer him legal guarantees in the proposal that Belgium would not be financially exposed.

But despite increasing diplomatic pressure for Belgium to cave, De Wever on Thursday only increased his hostility to the Commission’s plans. Expanding on his previous objections, the Belgian leader argued the Commission’s scheme would block a peace deal in Ukraine. If the EU’s plan does not come to fruition, the Russian assets will instead be used as a bargaining chip to bring Moscow to the negotiating table, rather than being paid to Kyiv, he said.

“Hastily moving forward on the proposed reparations loan scheme would have, as a collateral damage, that we as EU are effectively preventing reaching an eventual peace deal,” De Wever wrote in the letter.

After a prolonged standoff, the Commission is expected to finally put forward a formal proposal outlining the loan on Friday, or early next week. After failing to reach a deal in October, EU leaders are set to tackle the most sensitive issues in their next summit in mid-December.

While a majority of countries back the loan, De Wever is unconvinced.

“In the very probable event Russia is ultimately not officially the losing party, it will, as history has shown in other cases, be legitimately asking for its sovereign assets to be returned,” De Wever continued in the letter.

The Belgian leader restated the loan would trigger mayhem in the EU’s financial markets, and expose EU taxpayers to repaying the full amount if the assets are returned to Russia.

Instead of tapping the Russian reserves, De Wever suggested that the European Commission should issue €45 billion in joint debt to cover Ukraine’s financial needs in 2026 ― an idea that is unpopular among most EU governments because it involves using taxpayers’ money.

Restating his traditional position, the Belgian leader said he would agree to the loan only if governments agree to immediately stump up the full amount if Russia reclaims the assets.

“I will not agree unless these guarantees, as stipulated above, are delivered and signed by member states at the time of decision,” he wrote.