The EU's four biggest powers - France, Germany, Italy and Spain - have launched a joint initiative to try to unblock a long-stalled effort to reform the bloc's asylum policies. The proposal, made in a letter dated April 9 to two EU commissioners in charge of the reform and seen by AFP on Friday, calls for refugees who currently overwhelmingly land in Greece, Italy and Spain to be shared across the 27-nation union.

If approved by member states, this mechanism would be binding, the interior ministers of the four EU countries wrote. Exceptions would be only "for motivated reason" and "other measures of solidarity than relocation" would have to be substituted - suggesting perhaps giving money or material support to countries hosting refugees.

The lack of precision over the substitute measures is to assuage concerns by four eastern and central EU countries - Poland, Hungary, the Czech Republic and Slovakia - which reject orders to take in refugees, a diplomatic source said.

The letter was sent to commissioners Margaritis Schinas and Ylva Johansson. They are meant to come up with a new migration and asylum pact, something their boss, European Commission chief Ursula von der Leyen, promised would be published after Easter.

Work on the reform started in 2015, under the previous commission, but has butted up against "divergent positions" since then. The diplomatic source said the letter was important because it showed a narrowing of those differences among key countries and was "a signal of the ability to find a deal" acceptable by all 27 member states. Another European source called it "something we can build on in discussions," adding: "So far there are not many compromise proposals."

A Commission spokesman, Adalbert Jahnz confirmed the EU executive had received the letter but did not comment further beyond saying that work on the pact continued.

He did not say when the promised reform would be presented, pointing to the exceptional circumstances thrown up by the novel coronavirus emergency.