President Vladimir Putin on Tuesday likened Ukraine's incursion into Russia to the 2004 Beslan school massacre, in which some 330 people died in a hostage siege.

Putin visited the school for the first time in almost 20 years, paying tribute to the victims at memorials, including a cemetery and the site of the destroyed school, where Chechen militants took more than 1,000 people hostage.

Meeting mothers who lost children in the siege, Putin said that Russia's enemies are again trying to destabilise the country, referring to Ukraine.

"Just as we fought the terrorists, today we have to fight those who are carrying out crimes in the Kursk region," Putin said, referring to Ukraine's cross-border offensive that began two weeks ago.

"But just as we achieved our goals in the fight with terrorism, we will achieve these goals also in this direction in the fight with neo-Nazis," Putin added, sitting opposite three women from the Mothers of Beslan group.

"And we will undoubtedly punish the criminals, there can be no doubt of that," Putin added.

The Mothers of Beslan group has long called for an objective probe into the attack and the Russian authorities' response.

The September 2004 siege lasted some 50 hours, ending in a gunfight when Russian special forces stormed the building following explosions in the school gym, where the hostages were being held.

The siege in the Caucasus region of North Ossetia came amid a guerilla insurgency by Islamist Chechen separatists, branded "terrorists" by Putin.

Putin launched a major Russian offensive to quash Chechnya's armed bid for independence in late 1999, weeks before becoming president.

The war against the Chechen insurgency helped fuel Putin's initial popularity, but at the end of 2019 he described the Beslan siege as a "personal pain" that would remain with him for life.

Putin and the Kremlin were criticised for their handling of the attack at the time.

At the meeting with Putin, the Mothers of Beslan complained that Russia's investigation into the school siege has never been completed, the group's co-chairwoman Aneta Gadiyeva told the Agentstvo news outlet.

This part of the meeting, unlike Putin's remarks about Ukraine, was not televised.

Gadiyeva said Putin told the women that he had not known this and would ask the head of the Investigative Committee to intervene.

The European Court of Human Rights ruled in 2017 that Russia's handling of the siege had "serious failings" in terms of preventing the attack and its use of excessive lethal force and called on Moscow to take measures to establish the truth.

The attack came two years after Chechen fighters took hundreds hostage in a Moscow theatre, a stand-off which saw more than 130 killed – most by sleeping gas pumped into the theatre by Russian special forces.

On Tuesday, Putin laid red roses at the foot of a monument in the cemetery, where he bowed down to "honour the memory of the victims of the terrorist attack," the Kremlin press service said.

He also laid red roses at a monument to members of Russia's special forces who died during the storming of School Number One.

An "international cultural and patriotic centre for the prevention of terrorism" has been set up at the site of the former school, the Kremlin's press service said on Telegram. (AFP)