The Kremlin-backed news channel RT has been sanctioned by Ofcom for a series of misleading or biased programmes on the conflicts in Ukraine and Syria.

In a ruling publishing on Monday, Ofcom said the channel – previously called Russia Today – had breached the broadcasting code four times across three programmes.

The programmes include two episodes of the channel’s Truthseeker series, including one which alleged that the BBC had staged a chemical weapons attack by the Assad regime in Syria.

The ruling said the programme about reports on the BBC’s News at Ten and Panorama had misled viewers by suggesting a complaint made by a viewer represented a “massive public investigation” into the BBC’s reporting of the attack.

It also separately found that the programme had breached rules by failing to ensure the allegations were presented fairly and not giving the BBC the chance to respond to the allegations.

The RT programme, broadcast in March 2014, included allegations that the BBC had edited an interview with a Syrian doctor to misrepresent her comments about treating victims of an attack.

Ofcom did not consider the accuracy of the claims made in the Truthseeker programmes as the show is considered current affairs rather than news programming.

Another episode of Truthseeker claimed there was a government-backed genocide taking place in eastern Ukraine, while a half-hour standalone segment called Ukraine’s Refugees alleged the Ukrainian government was involved in killing civilians.

Ukraine’s Refugees featured only first-hand accounts, but the Ukrainian government’s response was limited to a six-second message shown at the end of the programme.

Both shows were deemed to have breached rules on impartiality. Truthseeker was cancelled in July 2014.

The rulings require RT to broadcast corrections detailing the findings.

An Ofcom spokesperson said: “Ofcom found that RT broadcast content that was either materially misleading or not duly impartial. These are significant failings and we are therefore requiring RT to broadcast two clear statements on our decision which correct these failures.”

The Russian government, which funds RT’s operations in the UK and elsewhere, has close ties to the Assad regime and separatist groups in Ukraine opposing the government in Kiev.

RT said it was disappointed with the regulator’s rulings.

“We are shocked and disappointed in Ofcom’s decision,” said RT editor-in-chief Margarita Simonyan. “The film about refugees was based entirely on first-hand accounts of the war victims.”