German govt: Navalny under police protection, Greece Turkey tension

Russian dissident Alexei Navalny remains in a Berlin hospital where he is being treated following a suspected poisoning, with special protective details on hand to ensure his safety.

German Chancellor's spokesman Steffen Seibert said authorities were waiting for the results of medical examinations on Navalny, who is in a critical but stable condition after being flown to Germany on Saturday from Siberia.

Berlin police and federal agents were posted at the downtown Charité hospital where the 44-year-old is undergoing treatment.

"It was clear that protective measures had to be taken after his arrival here. After all, this is a patient on whom a poisonous attack has been committed with a certain probability," Seibert said during a government news briefing.

A spokesman for the Foreign Ministry also announced on Monday that Foreign Minister Heiko Maas will visit Greece and Turkey on Tuesday.

"We are very concerned that these tensions are already straining relations between the EU and Turkey and that if these tensions continue to increase, a further escalation could have even more serious consequences," said spokesman Christofer Burger.

Greece said on Monday that it will conduct a navy and air force exercise in an area of the eastern Mediterranean where Turkey is prospecting for oil and gas in an area as the neighboring countries remain locked in a dispute over offshore energy rights.

Authorities said that the live-fire exercises would start on Tuesday southeast of the Greek island of Crete and end Thursday.

Turkey has a research ship escorted by warships surveying for oil and gas exploration in the area and said on Sunday that the work would continue through Aug. 27.

The Turkish government disputes Greece's claim to exclusive rights in the waters where the research vessel is working, arguing that islands should not be included in calculating sea boundaries between countries.