The broadcaster Aasmah Mir has quit the BBC and is understood to be joining Times Radio, as the new station prepares to launch in a bid to challenge Radio 4’s dominance.

Mir confirmed this weekend’s edition of Saturday Live on BBC Radio 4, which she co-hosts with the Rev Richard Coles, would be her final appearance on the morning programme.

“It’s been almost six years and it’s time for something new,” she said on Twitter, without giving any clues as to her future.

Individuals at Times Radio, which has been continuing to hire staff throughout the lockdown, said Mir was in line for a job at the talk radio station, which has been described as a commercial rival to Radio 4. Mir did not respond to a request for comment, although sources suggested the lineup for Times Radio was expected to be unveiled imminently.

Profile What is Times Radio? Show Times Radio is an upcoming radio station owned by Rupert Murdoch. It is intended to be a commercial rival to BBC Radio 4. The new station will be available on national DAB digital radio but will also try to take advantage of the rapid growth of smart speakers which are making it easier to try new stations. Times Radio has hired the BBC’s deputy political editor, John Pienaar, to front its new drivetime programme. Stig Abell, the editor of the Times Literary Supplement who is coordinating the launch of the station, said he hoped Pienaar’s hiring would help make it a “new destination for those people hungry for quality reporting and trusted, expert analysis”. There has been disquiet in the BBC that the station’s launch is being coordinated by Abell, who is helping to poach many of the BBC’s leading presenters while still regularly presenting Radio 4’s flagship arts programme Front Row. Jim Waterson Media editor

The station, which will run without adverts, aims to provide an alternative to the BBC’s talk radio services, while also encouraging people to buy paid subscriptions to the Times – in effect being considered as marketing spend for the outlet.

Mir’s decision could also help balance out the number of male presenters on the station. The launch is being overseen by Stig Abell, the editor of the Times Literary Supplement, who is expected to have his own show. Other names linked to presenting jobs include Matt Chorley of the Times’ Red Box newsletter.

Times Radio has already attracted attention for aggressive attempts to poach high-profile BBC radio presenters, especially given its owner Rupert Murdoch’s antipathy towards the broadcaster. Many have resisted the lure of a substantial pay rise to stay with the national broadcaster. One individual who turned down a job offer suggested they were put off when they realised how much extra broadcasting would be involved.

The only confirmed presenter to sign up to the new channel is the former BBC deputy political editor John Pienaar, who will present the afternoon programme on the station. More BBC staff have made the jump behind the scenes, including former Radio 5 live producer Tim Levell, who has been appointed as programme director.

The project, part of Murdoch’s push into UK commercial radio, is likely to be one of the few big media launches of the year, as the rest of the industry is facing a substantial contraction and job losses amid a collapsing advertising industry.

The arrival of Times Radio has caused concern within the radio department at Murdoch’s News UK headquarters, with talkRadio – at one time considered to be for the chop – moved out of its existing studio to make way for the new broadsheet-linked outlet. Rather than take it off air, News UK has decided to keep talkRadio, which has presenters including Julia Hartley-Brewer and Dan Wootton.

There have also been questions about how the station will fit with the Times’ separate and well-staffed new daily podcast team. The show is hosted by Manveen Rana and David Aaronovitch, and was developed separately to Times Radio.