Russia has marked Unity Day each November 4 since 2005, following a 2004 law signed by then-president Vladimir Putin. The holiday commemorates the liberation of Moscow from Polish-Lithuanian occupiers in 1612.
Unity Day effectively replaces celebrations of the Bolshevik Revolution, which had been held on November 7. Celebrations were moved forward by three days to avoid associations with the revolution.
"Organizing such merrymaking in the midst of a crisis is like having a feast during the plague," Communist Party lawmaker Valery Rashkin told RIA Novosti.
"November 7 is a holy day, the day of the revolution, a historical day. The initiators of this holiday [Unity Day] could not even create a historical rationale, and couldn't even choose a day. The recapture of the Kremlin [by forces led by Russia's Dmitry Pozharsky and Kuzma Minin] also took place on the seventh, so on the seventh we should be celebrating both national unity, and the anniversary of the revolution," he said.
To mark Unity Day, Russian President Dmitry Medvedev will lay flowers at the statue of Minin and Pozharsky in front of Saint Basil's Cathedral on Red Square. The president will also meet with representatives of non-governmental organizations in the Kremlin Palace.
The ruling United Russia Party has announced various public celebrations to be held throughout the country.
According to various surveys, most Russians are not aware of the historical meaning of Unity Day. However, the event has become popular with nationalist and far-right movements, who are set to hold several rallies in Moscow on Tuesday.
One of the rallies has been sanctioned by the authorities, and is to take place in the center of the capital. It is expected to draw about 5,000 people. The organizers have promised that the event will go ahead without incident.
"The main motto will be 'For a Russian Russia,'" Ilya Goryachev, a representative of the Russian Image movement, which is organizing the event with the People's Union, earlier said.
A number of other groups have said they will hold unsanctioned rallies. Police have said they will clamp down on any illegal marches.
The first "Russian March" was held in Moscow on November 4, 2005. It was the first legally- sanctioned, large-scale nationalist event in post-Soviet Russia.
In 2006, a planned National Unity Day march by nationalist groups was banned by Moscow authorities. However, far-right groups defied the ruling and marched. Some 200 people were subsequently arrested.
More than 70 people have been killed and some 300 injured in ethnically motivated violence in Russia so far this year, the deputy head of a think tank dealing with the problem said in late September.
Russian media reported late last year that teenage ultra-nationalist gangs may have been responsible for up to 50 race-hate murders in Moscow in 2007.