SAINT PETERSBURG (AFP) - President Vladimir Putin said on Monday the memory of Russia's heroism and sacrifice during World War II must endure as the country marked the 70th anniversary of the lifting of the Nazi siege of Leningrad.

The 61-year-old leader said the world should never forget "the courage and heroism of the Soviet people and residents of Leningrad" as he participated in commemorative ceremonies in his native Saint Petersburg, known as Leningrad under the Soviet Union.

The near two-and-a-half-year siege - 872 days in all - by Nazi forces between September 1941 and January 1943 is seared into the national consciousness as one of the darkest moments in Russian history.

Taking Leningrad was a strategic part of Adolf Hitler's ultimately failed plan to eliminate the Soviet Union as a threat to German domination of Europe.

The assault is considered one of the most devastating sieges in history, with German commanders calculating that starvation would be their most effective weapon.

"360,000 civilians died in Leningrad over a period of just four months from the end of 1941 to the start of 1942," Mr Putin said at a meeting with war veterans and survivors of the siege.

"Britain lost nearly the same amount in the entire World War II.

"Can you imagine the difference between the victims that the Soviet Union and other countries of the world laid on the altar of common victory?"

Surrounded by several dozen survivors of the siege, Mr Putin earlier visited the famed Piskaryovskoe Memorial Cemetery, the main memorial to the victims of the siege.

He also honoured the memory of his elder brother who died during the blockade and was buried at the cemetery in a mass grave, the Kremlin said.

The president also laid flowers at a memorial on the banks of the Neva River marking the site of one of the most important battles during the siege in which his father participated as a soldier.

The blockade of the former imperial capital claimed the lives of more than a million people, according to historians.

Most of them died of hunger and exhaustion during an extremely cold winter at the beginning of the siege from 1941 to 1942 when rations fell to just 125 grams of bread per person for white-collar workers and municipal heating was switched off.

People were forced to eat pets, earth and glue and some even resorted to cannibalism.

Dead bodies littered the streets for days as the survivors were too weak to bury the deceased.

Early Monday, some 1,500 people took part in a military parade showcasing Soviet-era war-time T-34 tanks as well as modern Iskander ballistic missiles.

In the run-up to the anniversary, the local authorities put together an exhibition reconstructing part of a street in the city centre with siege-related artifacts like sandbags, boarded-up windows, theatre bills and old cars and trolleybuses.

"When I look at the chronicles and the pictures I can barely hold back tears," said Madam Natalia Zvereva, 60, who brought her grandchild to see the exhibition.