UPDATE 1-Navalny must receive medical aid, EU tells Russia

(Updates with statement, letter, ministers)

By Robin Emmott and Sabine Siebold

BRUSSELS, April 19 (Reuters) - Russia must allow Kremlin critic Alexei Navalny, who his allies say is in a critical health condition in prison, to have access to proper medical care, the European Union's top diplomat said on Monday as EU foreign ministers pressed for his release.

Navalny, 44, a prominent opponent of Russian President Vladimir Putin, announced a hunger strike at the end of March in protest at what he said was the refusal of prison authorities to treat him properly for acute back and leg pain.

"We make the Russian authorities responsible for the health situation of Mr Navalny," Josep Borrell said before a video conference of the EU's 27 foreign ministers, who on Sunday released a joint statement warning of the risks to Navalny's life.

Leading EU lawmakers also spoke out.

"Act now, or the blood of Mr Navalny will forever be on your hands," said Manfred Weber, who lead's the European Parliament's biggest grouping, the European People's Party.

Navalny, who the West says has been wrongly jailed and should be freed, returned to Russia in January after recovering from what German doctors say was a nerve agent poisoning.

Lithuanian Foreign Minister Gabrielius Landsbergis said the EU, which has already imposed sanctions on Russians it deems responsible for Navalny's poisoning, said the EU should be ready with a special medical team.

Two allies of Navalny, Vladimir Ashurkov and Leonid Volkov, wrote to the EU ministers to urge them to discuss Navalny's health at their next meeting on Monday, according to a copy of the letter seen by Reuters.

Borrell said ministers had received it.

The letter raised similar health concerns to those voiced on Tuesday by Navalny's wife Yulia, who said after visiting him in prison that he was having difficulty speaking and had lost more weight.

"Alexei's health is steadily deteriorating," the letter said, citing an unofficial copy of test results that showed spinal problems.

Navalny was jailed in February for two-and-a-half years for charges of parole violations that he called politically motivated. Russia has said it has yet to see evidence he was poisoned.

Staff at the Russian prison said they have offered Navalny proper treatment, but that he refused it. (Reporting by Robin Emmott in Brussels and Sabine Siebold in Berlin, Editing by Angus MacSwan)