Dmitry Medvedev, the Russian president, has submitted to parliament a draft law which would extend the presidential term of office, a Kremlin spokeswoman said.

Medvedev said last week he wanted to increase the presidential term from four to six years to give the head of state more time to push through reforms.

Some political analysts have said the change could be part of a plan for Vladimir Putin, the Russian prime minister and former president, to return as president, a post he held for eight years until his second term ended this year.

"The President of Russia .... has sent to the State Duma [lower house] draft laws on amendments to the constitution of the Russian Federation 'on changes to the term of office of the president of the Russian Federation and the State Duma'," a Kremlin statement said on Tuesday.

The Kremlin has said the proposed change would not apply to the term Medvedev is serving now.

RIA Novosti news agency last week reported Igor Shuvalov, the first deputy prime minister, as saying: "This should not be seen as a strengthening of presidential  power. It should be seen as a balanced model for a new political construct."

Putin was prevented by the constitution from running for a third consecutive term, but he would be able to stand in elections in 2012 when Medvedev's term is due to end.

Last week, a spokesman for Putin said that media reports suggesting he would replace Medvedev as head of state after an early presidential election were "absolutely without foundation".

Medvedev also submitted a draft law to extend the term of the State Duma, or lower house of parliament, from four to five years, the Kremlin spokeswoman said.

Putin leads the United Russia party which dominates the Duma.