RT, the Kremlin-backed news channel that broadcasts in the UK, is facing seven new investigations after Ofcom said that it had seen a significant rise in potentially problematic material since the poisoning of Sergei and Yulia Skripal.

Ofcom said it had monitored RT intensively since the news became public and was now examining a number of instances in which the channel potentially breached broadcast laws on impartiality.

It said that not all cases necessarily related to the Salisbury attack.

The UK broadcast regulator repeated that it could ultimately revoke the channel’s licence to operate in the UK following the conclusion of its investigation, forcing the channel off air.

“Since the events in Salisbury, we have observed a significant increase in the number of programmes broadcast that we consider warrant investigation as potential breaches of the broadcasting code,” said the regulator, which promised to publish its conclusion as soon as possible.

“Ultimately, we may decide that the licence should be revoked because the licensee is not fit and proper, on broadcasting compliance grounds.”

British intelligence officials have concluded that it is highly likely that Russia was responsible for the Salisbury attack, prompting dozens of countries to expel Russian diplomats in solidarity with the UK. Moscow has strongly denied any involvement and has repeatedly disputed the British version of events.

In the immediate aftermath of the attack there were calls from MPs for RT, originally known as Russia Today, to be taken off air. Tom Tugendhat, the chair of the Commons foreign affairs select committee, called it a hostile agent carrying out information warfare, and the former Labour minister Chris Bryant asked: “Can we just stop Russia Today broadcasting its propaganda in this country?”

RT accused its critics of treating it as a political pawn. It said at the time: “In one fell swoop they are doing away with any concept of press freedom in the UK”.

RT’s willingness to give a platform to figures ignored by larger mainstream news channels has made it a favoured home for political figures who struggle to get a hearing elsewhere. The former SNP leader Alex Salmond hosts a show on the network, and Nigel Farage has been a regular guest.

Following the Salisbury poisoning, the shadow chancellor, John McDonnell, saidit was no longer appropriate for Labour MPs to appear on the network, because “what we’re seeing from Russia Today at times goes beyond objective journalism”.

The channel’s UK audience remains relatively small, reaching just 1% of British adults a week, according to Barb viewing figures. It does, however, have a substantial online following.

A spokesperson for RT said: “We are pleased to see that Ofcom has acknowledged RT’s compliance record has been in line with other broadcasters – putting to bed any of the salacious political statements and challenges made against our channel. Our editorial approach has not changed since the events in Salisbury, and we will be directly addressing this matter with the regulator.”