Russian president-elect Dmitry Medvedev has predicted some people might try to challenge his presidency, the first acknowledgement of what could be a simmering turf war among Kremlin clans.

Kremlin-watchers say factions close to outgoing president Vladimir Putin are nervous about Medvedev running Russia and want to leave the way open for Putin to return if his replacement does not prove up to the job. Putin endorsed Medvedev, a 42-year-old former law professor, to be president.

The outgoing president is to stay on in the junior role of prime minister. Their double act is unusual for Russia with its tradition of a single, strong ruler.

"As for concerns (about the Putin-Medvedev partnership) then they, of course, exist and will continue to exist," Medvedev said in an interview, extracts of which were published on Thursday on his official Internet site www.rost.ru/medvedev. "People are going to test it for its durability. That is obvious. I am sure that there are some people who are going to interpret this arrangement in their own way and who will look for holes in it.

"They will do what people in politics do, that is political manoeuvring. But we are sufficiently grown-up lads to handle that. We will manage," he said in the interview, for a forthcoming biography.

He did not spell out that any challenge would come from inside the Kremlin. But with Russia's opposition parties weak and marginalised, government infighting, for now at least, appears to offer a bigger test after he takes power in May. Analysts say resistance to a Medvedev presidency is led by a loose grouping of Kremlin insiders, commonly referred to as the "siloviki" who, like ex-KGB spy Putin, have backgrounds in the security services.

Coming from academia and business, Medvedev is regarded by the "siloviki" as an outsider. They had hoped Putin would find a way to stay on in office, or endorse one of their own number as his replacement.

In the interview, Medvedev said he had no objection to former security service officers holding top government posts.

"They are people, just like everyone else. They should not be demonised or made out to be sacred. Sometimes there are more of them in power, sometimes fewer," he said.