Ukraine’s surprise incursion into Russia’s Kursk region has continued into a second day, prompting Vladimir Putin to convene a meeting with his top defence and law enforcement officials.

A report from one Russia military blogger suggested Ukrainian forces had advanced northwards, possibly as far as nine miles (15km) from the border, along a highway north of the border village of Sverdlikovo, but this could not be verified.

Official and unofficial Russian sources reported that a force of several hundred soldiers had crossed a lightly defended part of the border on Tuesday morning. Russia’s defence ministry said on Wednesday that the attack was being neutralised.

It had claimed Russian forces had repelled the raid on Tuesday, but acknowledged at lunchtime on Wednesday that fighting was ongoing. It said they had used air and missile strikes and artillery fire against the invaders, inflicting 260 casualties and knocking out 50 armoured vehicles.

In televised remarks at the start of a meeting with members of the Russian government, Putin described the raid as a major provocation and said he would discuss it with top security officials later in the day.

Several Russian bloggers reported that Putin would hold a meeting of the Russian security council at 1pm Moscow time (1100 BST) in response to the latest military developments, but there was no official confirmation.

The acting governor of Kursk oblast, Alexei Smirnov, said he had reported the operational situation to Putin. Civilians were being evacuated from frontline areas and 300 people were housed in temporary accommodation overnight.

Ukrainian officials have remained quiet as the incursion has developed, anxious perhaps not to appear triumphant or give away too much information about Kyiv’s intentions.

Russia said the attack had begun at about 8am on Tuesday morning, when Ukrainian troops crossed the border between the villages of Nikolayevo-Daryino and Oleshnya, with the apparent intention of heading both north and east.

The attack is most likely to be an attempt by Ukraine, whose defences are stretched on the eastern Donbas front, to divert some Russian forces to defend a part of the frontline that has been largely inactive since early 2022.

Critics in Ukraine, however, argue that such assaults serve no long-term military purpose. Anti-Kremlin Russian groups launched attacks from Ukraine into Belgorod and Kursk regions in March, but were repelled with no strategic gain.

Information is scant, but this time the operation appears to be an attack by Ukraine’s military rather than Russian opposition groups. Russia said it was led by Kyiv’s 22nd mechanised brigade.

Fighting was taking place in and around the town of Sudzha, about 6 miles from the border. A local Russian Telegram channel released a short video showing bombed out rural homes, which it said demonstrated the “situation today”.

The main operational gas pipeline into Europe runs near Sudzha, where a metering station monitors the reduced Russian supplies to countries such as Austria and Hungary. Ukraine has allowed gas to continue flowing through the pipeline as part of a contract that expires at the end of 2024.

Other online speculation suggested that a target of the incursion could be the Kursk nuclear power plant, but the facility is 35 miles from the border and a long way from what a force of several hundred – or thousand – would be capable of.

Russia has been pouring soldiers into Ukraine. Its force in the country is estimated at about 520,000, two to three times the size of the original invasion. Ukraine, meanwhile, is finding it challenging to mobilise fresh recruits and is being pushed back in certain parts of the eastern front, particularly the central Donbas towards Pokrovsk.

Additional reporting by Pjotr Sauer