MOSCOW (REUTERS) - Russian police have traced opposition politician Alexei Navalny's movements and what he drank before falling ill in Siberia last month, and are trying to locate a witness who has left the country, the interior ministry said on Friday (Sept 11).

The ministry said it was preparing another request for legal assistance from Germany, where Mr Navalny was airlifted to hospital last month after what Berlin says was a poison attack on him with a Novichok nerve agent.

In a statement, the interior ministry's transport department in Siberia said it wanted to send investigators to work alongside German colleagues on the case, after reports that Mr Navalny had emerged from a coma.

"This request will include an application for the possible presence of Russian internal affairs investigators... and a Russian specialist when German colleagues are conducting investigations with Navalny, doctors and experts," the ministry said in a statement.

It also requested permission to ask clarifying and additional questions.

The request appeared to have no chance of success, given that Germany says it has already established the presence of Novichok and demanded explanations from Moscow - a call strongly echoed by other Western countries.

Some German politicians have called for additional sanctions against Russia.

Russia has not opened a formal criminal investigation and is sticking to its position that it needs hard evidence from Germany that Mr Navalny was indeed poisoned.

Transport police in Tomsk had established a timeline of events leading up to Mr Navalny falling ill, the ministry said. It listed a hotel, restaurant, flat and coffee shop Mr Navalny had visited, and said he had drunk wine and an alcoholic cocktail.

In the days following Mr Navalny's illness, his spokesman strongly denied allegations that he had consumed alcohol.

The ministry said police had interviewed five of the six people it said accompanied Mr Navalny on the journey when he fell ill.

It said it was looking for a sixth person it named as Ms Marina Pevchikh, a British resident who flew to Germany on Aug 22 and whose whereabouts it said were currently being established.