Russian presidential spokesperson Dmitri Peskov described the leaks found at the Nord Stream gas pipelines earlier this week as 'some kind of terrorist act', while speaking in Moscow on Thursday. 

"The unprecedented nature of this event seems to be some kind of terrorist act, possibly at the state level," he claimed. "Of course this calls for very active co-operation. This is an extremely dangerous situation that needs to be dealt with urgently," Peskov continued.

The Kremlin spokesperson was also asked if Russia and the US could work together on the investigation.

"It is impossible to answer this question because we do not have any substantive contacts and co-operation on the security level," he replied. 

Leaks were discovered in the Nord Stream lines by both Denmark and Sweden earlier this week.

On Tuesday, Russian Foreign Ministry spokesperson Maria Zakharova said that the incidents occurred in an area controlled by US intelligence services.

NATO, the EU and US have blamed 'sabotage', but while not directly accusing Russia, Peskov previously dismissed insinuations in the press as 'predictable' and 'absurd'.

First Deputy Permanent Representative of the Russian Federation to the United Nations Dmitri Polyansky also discussed convening an urgent meeting of the organisation's Security Council on Friday, in connection with the pipeline incidents.

Meanwhile, at Thursday’s briefing, Peskov also announced "the signing ceremony for the new territories' accession to the Russian Federation", to be held on Friday at the Grand Kremlin Palace.

The local governments of the Donetsk and Lugansk People’s Republics, as well as those established in Kherson and Zaporozhye after they came under Russian control, held referenda earlier this week on joining the federation.

The regional election commissions announced all had voted overwhelmingly in favour of the proposal, which Kiev and its Western allies dismissed as a 'sham'.

France and Germany vowed not to recognise the results, while EU Foreign Policy Chief Josep Borrell claimed those involved in organising them 'will be held accountable'.

US President Joe Biden said that Russia had 'violated the basic principles of the UN Charter' and also made 'open nuclear threats against Europe.'

Moscow launched the military offensive in Ukraine earlier this year, after recognising the independence of the DPR and LPR.

Kiev condemned the action, while President Volodymyr Zelensky ordered martial law and full mobilisation in February.