Emily Thornberry, a candidate for the Labour leadership, has said senior advisers should pay the price for the party’s disastrous election showing, rather than the junior workers who are losing their jobs.

The shadow foreign secretary, who declared her candidacy on Wednesday, called for a different approach amid anger among Labour employees that two senior figures, Seumas Milne and Karie Murphy, are still in their posts.

The row over job losses later blew up in the shadow cabinet, as some senior figures raised concerns that they had not even been told in advance that some of their long-serving advisers were being offered redundancy packages by the central party.

Speaking on BBC Radio 4’s Today programme, Thornberry said she was “not naming anyone”, but she appeared to be talking about Milne and Murphy, who are both on permanent contracts with the party.

“People know who it is that I’m talking about. But the truth is now we’re in a position where there is talk of redundancies amongst more junior staff … that it may be necessary for them to be made redundant,” she said. “And yet those that made the very decisions about the general election don’t seem to be under threat.”

Details of the package targeting at least 20 staff can be disclosed for the first time. Those asked to leave will receive a month’s worth of pay, plus two weeks of their pay for every year of service, but would have to agree not to work for Labour for a year.

A party official said contracts of employment are tied to the leader of the party or to shadow cabinet roles which end with Corbyn’s leadership. “That’s the nature of political adviser contracts. These are not redundancy packages. But the party is still providing an option to leave with a payment, even though we’re not required to do so.”

However, a party source said the money on offer and the timing of the job losses has led to anger and resentment. “For some, the offer will pay less than working out their notice.

“Doing this just before Christmas has led to suspicions that it is being deliberately mishandled so they can destroy morale even further and force as many people out as possible.”

Milne is Jeremy Corbyn’s director of communications and strategy, and Murphy was Corbyn’s chief of staff before she moved to Labour HQ to run the election campaign.

Most of those who work for the leader of the opposition are on time-limited contracts while Corbyn remains leader. It is understood that Milne and Murphy were moved across to permanent contracts some months ago.

An email sent by Labour’s HR director, Joe Perry, on Wednesday and subsequently leaked to the Guardian said a “reduction in Short money through which we fund a lot of our political roles” meant changes would have to be made.

Short money is funded by the taxpayer and allocated according to the party’s parliamentary strength. It was worth £8m to Labour in 2018, the party’s latest annual report showed.

A Labour spokesman said: “We don’t comment on staffing matters.”

Jess Phillips, another possible leadership contender, urged Labour to behave as the “party of the workers” when dealing with staff. She said: “People often forget party staff and the staff of MPs who lose. [The] Dickensian nature of giving marching orders before Christmas is heartbreaking, especially as it appears those with top jobs are protected. These people were not the authors of this loss, they did their very best.”

Last year Milne was paid £104,000 and Murphy – a friend of the Unite leader, Len McCluskey – received £92,000.