MOSCOW, Oct 1 Russian President Vladimir Putin said today he could one day assume the pos

MOSCOW, Oct 1 (Reuters) Russian President Vladimir Putin said today he could one day assume the post of prime minister, giving a clear sign of how he plans to keep power after his second term ends next year.

Speaking at a congress of the main pro-Kremlin force, United Russia, Putin announced he would head the party's list for December's parliamentary elections, guaranteeing him a place in the State Duma (lower house of parliament).

''As far as heading the government is concerned -- this is a quite realistic suggestion but it is still too early to think about it,'' Putin said.

''Two conditions must be met first - United Russia must win the election and a decent, capable and modern person with whom I work as a team should be elected as president,'' he added.

Initial reaction from financial markets was positive.

''Irrespective of one's view of Putin's democratic credentials, markets respect the stability and prosperity he has brought to Russia, and should react positively to the latest development,'' said Tim Ash, an emerging markets economist at Bearns Stearns in London.

All polls published so far give United Russia a huge lead for December's vote, with at least 50 per cent of the vote. The number two force, the communists, poll around 10-20 per cent.

STANDING OVATION Putin's own popularity and the Kremlin's control over politics and the media virtually guarantees whoever he anoints as his successor a resounding electoral victory in the presidential vote next March.

Putin has not yet indicated whom he will back as his successor.

Speculation has centred on first deputy prime ministers Dmitry Medvedev and Sergei Ivanov, newly-appointed prime minister Viktor Zubkov and a host of lesser figures.

Commenting on a suggestion he should head the United Russia party list for the December Duma elections, Putin said to a standing ovation: ''I with gratitude accept your proposal''.

The head of United Russia's central committee, Andrei Vorobyov, said Putin's decision to head the list meant the party would secure an ''unconditional victory'' in December with at least 300 of the 450 seats in the Duma.

Putin's term as president ends next year and he is barred from running for a third consecutive term by the constitution.

Putin served as prime minister in 1999, using the post as a stepping stone to the presidency he won after President Boris Yeltsin's resignation.

Putin's future intentions have been the subject of intense speculation, particularly after the president made clear earlier this year that he intended to keep an active role in politics after he left the presidency.

Political analysts have speculated in recent months that Putin might deliberately choose a weak and loyal successor as president and continue ruling the country from a key position such as prime minister.

''This was the most logical decision,'' said Gleb Pavlovsky, who heads the Kremlin-connected Effective Politics Foundation, commenting on Putin's remarks.

''It finally removes the so-called succession problem which suggested that Putin will have to hand over his influence to someone and go into the shadows after stepping back.'' ''This is a revolutionary step because for the first time since 1991, the real influence may turn out to be elsewhere outside the Kremlin. There will be a president in the Kremlin, but not necessarily a national leader.'' Investors agreed that if Putin became premier, he would remain as Russia's key figure.

''Putin will be in effect the head of state, it will just be as prime minister,'' said Ian Hague, a partner at Firebird Management in New York which has $1 billion invested in Russia.

''The market will like it; the market likes whatever Putin does.'' Putin has presided over seven successive years of rapid economic growth which has dramatically boosted living standards and given foreign investors the opportunity for huge profits. He has been criticised in the West over his human rights record and over tight restrictions on the media and opposition.

REUTERS AM BST2118