Russia has sent interior ministry troops to Moscow and increased the alert level of security forces after a protest of thousands of people opposing Vladimir Putin, officials said on Tuesday. "They (the troops) have just one aim -- to ensure the security of the citizens," interior ministry forces spokesman Colonel Vasily Panchenkov told the Interfax news agency while a police spokesman said the security forces were now on a "heightened regime" of alert. "The number of troops deployed is determined by the Moscow police," Panchenkov added, without giving numbers. Russian News Service radio, citing its listeners, said several trucks filled with troops were heading into the centre of Moscow along the city's main thoroughfares. A spokesman for Moscow police said that up to 4,000 police and interior ministry troops would be deployed to ensure order during several planned rallies in the Russian capital on Tuesday. "There's nothing extraordinary going on," the spokesman told AFP, saying the troops deployed in the streets would be from several military units. Meanwhile, a spokesman for the interior ministry told the RIA Novosti news agency that the strengthened security regime would be kept in place until the official end to vote counting from Sunday's polls. Several thousand people took to the streets in central Moscow late Monday despite pouring rain for a rally against the results of Sunday's elections in which Putin's United Russia party won but with a sharply reduced majority. Pro-Kremlin youth organisation Nashi was set to stage a mass rally on Tuesday expected to attract thousands of supporters banging drums near the Kremlin walls to show their backing for United Russia.