Doctors say opposition leader, who is on hunger strike, is in danger of a heart attack or kidney failure

Alexei Navalny has been transferred to a prison hospital as concerns have grown among supporters that the opposition leader is dangerously ill and could die “at any minute”.

Navalny’s transfer came after his doctors released paperwork showing that the Kremlin critic, who has been on hunger strike for nearly three weeks, said he was in danger of a heart attack or kidney failure.

Seeking to designate organisation as extremist group is most sweeping assault on opposition supporters yet

The Moscow prosecutor’s office has announced that it will seek to designate Alexander Navalny’s Anti-Corruption Foundation and his regional political headquarters as “extremist groups”, moving to in effect liquidate the jailed opposition leader’s political organisation in Russia.

It is the most sweeping assault yet on supporters of Navalny, and comes after his two-and-a-half-year sentence on embezzlement charges and the arrest of his top aides on various charges following large protests in January and February.

Opposition leader faces accusations over nationalist past but allies call for support to ensure his safety

The Kremlin is taking aim at Alexei Navalny’s reputation, as the opposition leader was sent to a prison colony in Russia, a journey into a “grey zone” where supporters say he will need maximum international support to ensure his safety.

For years Navalny was a phantom in Russian state media, his name studiously absent from the lips of top officials and news anchors. A favourite game among the opposition was to write his name on a snowbank – municipal workers would often arrive shortly after to sweep it away.