The assisted dying bill would be strengthened by plans for cases to be signed off by experts rather than a judge, the MP behind the law change has said.

The proposed law for England and Wales currently says a High Court judge must check each person is eligible and has not been coerced into making the decision to die.

But Kim Leadbeater, the Labour MP proposing the bill, will suggest replacing this with a panel of experts who would oversee applications.

It comes after concerns were raised over the court’s capacity to hear each individual case.

Leadbeater told the BBC adding “extra expertise” would improve the bill.

But some opponents have criticised the move as watering down the bill’s safeguards.

Conservative MP Danny Kruger – a leading critic of the bill – said while he welcomed the idea of more experts being involved in the process, he questioned whether they would be impartial like a judge.

He said concerns about the court’s capacity to hear individual cases was “a problem for the bill”, which should not be proceeding “without adequate judicial safeguards”.

Leadbeater said the panel of experts “would be professional people doing a professional job”.

She said some would say the bill now had “too many safeguards”.

“I’ve had emails saying why are you making this so difficult? Because we must remember at the heart of this is a terminally ill person who wants choice,” she added.

If approved, the bill, which is currently being considered by MPs, would allow terminally ill adults expected to die within six months to seek help to end their own life.

The new proposal will be voted on by a committee of MPs scrutinising the bill. The members were chosen by Leadbeater and the majority support the legislation.

It comes as the committee begins the process of going through the bill line by line.

Under Leadbeater’s proposal, the panel reviewing each application would be chaired by a senior legal figure, but not necessarily a judge, and would also include experts such as psychiatrists and social workers. Their decision could, if necessary, be reviewed by the High Court.

The panels would be chosen by a Voluntary Assisted Dying Commission, led by a High Court judge or senior former judge.

The commission would oversee all cases for an assisted death and report annually on the number of applications and how many were approved and rejected.

Ministers and officials have been closely consulted on the change, although the government technically remains neutral on the bill. Civil servants are drafting the amendment, which will be published later this week.

Leadbeater argued this was not removing judicial scrutiny but changing it to a “judge plus” model.

However, she previously hailed the role of the High Court as part of “three layers of scrutiny” that made it “the strongest, most robust piece of legislation on this issue in the world”.

The committee of MPs scrutinising the bill heard three days of oral evidence from experts two weeks’ ago, including some who raised concerns about the proposed role of the High Court in signing off applications.

Retired High Court judge Sir Nicholas Mostyn told the panel he thought it would be “impossible” for the High Court to rule in every assisted dying case.

“You’re talking about nearly three quarters of the entire Family Division [Court] doing nothing but this,” he said.

He added it should be done “by a panel set up… for each case, a doctor and a lawyer, they have to agree, and they check everything has been done lawfully”.

Leadbeater said she agreed with the need for other professionals to be involved in the checks.

“This bill already contains the strongest safeguards anywhere in the world, but I promised to give close attention to the advice we have received on how the bill could be made even stronger, and that is what I have done,” she said.

However, Liberal Democrat MP Sarah Olney, who sits on the committee and oppose the bill, said the version of the legislation initially passed by the House of Commons in November “specifically gave provision for a High Court judge” to sign off cases “and many MPs voted for it on that basis”.

“So to make this really profound change at this time makes it very, very difficult for the committee to decide whether this is the right thing or not in order to improve the bill,” she told BBC Breakfast.

More than 300 amendments have been tabled, with more expected in the coming weeks.

Among those to be debated on Tuesday is one tabled by Liberal Democrat MP Tom Gordon to allow those with a neurodegenerative illness, such as Parkinson’s, to access an assisted death with 12 months to live. The bill currently restricts assisted dying to those with a terminal illness with six months or less to live.

Gordon told BBC News: “This bill is about ensuring people facing painful deaths from terminal conditions can have the choice of how they die.

“For those with neurodegenerative conditions, in their last six months, it may be too late for them to engage in the process of applying.”

It is understood Leadbeater does not support expanding the scope of the bill to include those with 12 months to live.

MPs backed proposals to legalise assisted dying in England and Wales in November, by a majority of 55.

However, it will be debated further by the House of Commons and Lords later in the year, and the final version requires the approval of both before it becomes law.