Tom Watson has hit out at the “hard-left” in Labour and told Jeremy Corbyn to reshuffle his frontbench team to include MPs from across the party.

The intervention of Labour’s deputy leader came after seven MPs, including Luciana Berger and Chuka Umunna, quit the party in protest at Corbyn’s leadership.

“I love this party, but sometimes I no longer recognise it,” Watson said in a video message on Monday afternoon. “We are losing members and now losing MPs.”

Watson said Labour under Corbyn had “yet to convince the nation” it had answers to the “troubling questions” facing the country – including Brexit.

“The frontbench once again needs to reflect the balance of opinion within the Parliamentary Labour Party,” he said.

Addressing the decision of MPs to quit the party, Watson warned more could follow.

“I confess I feared this day would come. And I fear now, that unless we change, we may see more days like this,” he said.

“There are those who are already celebrating the departure of colleagues with whom they disagree.

“The tragedy of this hard-left is that can be too easily tempted into the language of heresy and treachery.

“Betrayal narratives and shouting insults at the departed might make some feel better briefly, but it does nothing to address the reasons that good colleagues might want to leave.”

On Monday morning Umunna, Berger, Chris Leslie, Angela Smith, Gavin Shuker, Mike Gapes and Ann Coffey dramatically quit Labour over issues including Brexit and anti-Semitism in order to sit as The Independent Group in Parliament.

Watson’s reaction was in stark contrast to other leading Labour figures. John McDonnell, the shadow chancellor, challenged the MPs to do the “honourable thing” and stand in by-elections.

And Unite union boss Len McCluskey, a close ally of Corbyn, hit out at the “splitters” who had “no stomach for a fight for Labour’s core values”.

Tory Party chairman Brandon Lewis said the resignations confirmed that Labour had “changed irreversibly” under Corbyn.