The BBC has said it is “urgently reviewing” comments made on air by newsreader Martine Croxall following Boris Johnson’s exit from the Tory leadership race.

The presenter was accused of breaching the broadcaster’s strict impartiality rules after she asked if she was “allowed to be this gleeful” during Sunday evening’s newspaper review on the BBC News channel, which came shortly after the former prime minister announced he would not be standing to reclaim his old job.

“Well this is all very exciting isn’t it?” she told viewers: “Am I allowed to be this gleeful? Well I am.”

In her first question to her guests, Croxall also remarked: “Can we even show you the front pages just yet, have they arrived? No they haven’t arrived.

“It’s all a little bit, you know, lastminute.com isn’t it? Because all the front pages were probably out of date by the time we received them.”

Croxall also suggested during the programme that her comments could have breached BBC guidelines.

Responding to a guest’s joke aimed at Johnson, she said: “I shouldn’t probably (laugh). I’m probably breaking some terrible due impartiality rule by giggling.”

Her comments – which aired around 90 minutes after Johnson’s announcement – attracted criticism from some viewers and Tory MP Nadine Dorries on social media, claiming they displayed bias.

A statement from the broadcaster said: “BBC News is urgently reviewing last night’s edition of The Papers on the News Channel for a potential breach of impartiality.

“It is imperative that we maintain the highest editorial standards. We have processes in place to uphold our standards, and these processes have been activated.”

The Telegraph and Press Association also reported Martine has been taken off air for an “undefined period”, although the BBC has not officially confirmed this.

The BBC would not verify this claim when contacted by HuffPost UK.

On Twitter, Croxall told one viewer to consider the “context” of her remarks, later clarifying: “The rollercoaster of politics. Fascinating to report on.”

When another Twitter user said they expected her comments were “journalistic excitement and not relief, like most of the viewers”, she replied: “Very much the former!”

On Monday, it was announced that Rishi Sunak had won the Conservative Party leadership contest and will become the next prime minister.

The former chancellor secured the overwhelming support of MPs and will be installed as PM without a vote of the party membership.