TENSION between left-wing political rivals burst open this week after new Labour MP Tulip Siddiq accused Green councillor Sian Berry of “neglecting” her constituents by running to be London Mayor.

In a surprising choice of target ahead of next May’s City Hall elections, Ms Siddiq used a prime television appearance to question Cllr Berry’s capacity to run for mayor and be a local councillor at the same time.

Her comments have been seen as a sign of the rivalry brewing following Jeremy Corbyn’s election as Labour Party leader and the chase to attract left-leaning voters.

“I’m very surprised because the Green candidate is actually a Green councillor in Camden – the only Green councillor we have in the borough who is now going to be neglecting her duties,” Ms Siddiq said.

She was speaking on the BBC’s Sunday Politics over the weekend, having been dispatched by the party to provide some puffy support for Sadiq Khan’s campaign.

But Cllr Berry, who foiled Labour hopes of a clean sweep of councillors in Highgate ward at last year’s Town Hall elections, accused Ms Siddiq of having double standards over who should – and should not – run for Mayor.

“Have Sadiq Khan or Zac [Goldsmith, possible Conservative candidate] resigned as MPs yet?” she said. “Has Caroline [Pidgeon, Lib Dem mayoral candidate] resigned from the London Assembly.”

Ms Berry later added that she was sure “Labour would like it if I did neglect the scrutiny of the council I do.”

She appeared on the main stage at the Green Party conference in Bournemouth on Sunday, using the opportunity to criticise the lack of affordable housing built into the redevelopment of King’s Cross.

“As a councillor in Camden I meet people every week in severe housing need… they want to know why there aren’t new homes for them to move into,” she told delegates.