Grenfell Tower families have raised concerns to the PM about a potential conflict of interest involving a member of the inquiry into the disaster.
Benita Mehra will join chairman Sir Martin Moore-Bick for the inquiry’s second phase, which begins this year.
The Guardian has revealed Ms Mehra ran a charity that received funding linked to US firm Arconic, which supplied the cladding that helped the fire spread.
Seventy-two people died during the tower block fire on 14 June 2017.
Shah Aghlani, who lost his mother and aunt in the fire, told the BBC: “We have to look into it and see what the facts are and, if there’s a conflict interest, I’m afraid she has to go. She has to be replaced.
“She’s going to be sitting on panel judging and analysing things and we can’t have any sort of conflict of interest.”
He added that, in a meeting with bereaved families on Thursday, Prime Minister Boris Johnson promised to “listen, look into it and he’d come back to us”.
A report – following the first phase of the public inquiry into the fire – found in October last year that the tower block’s cladding did not comply with building regulations and was the “principal” reason for the fire’s rapid and “profoundly shocking” spread.
Arconic said the grant was made by its charitable arm, the Arconic Foundation, which is “an independently endowed and managed foundation”.
A spokesman added: “It’s part of Arconic Foundation’s mission to create access to these fields for girls and women all over the globe. The grant we awarded in 2017 to this particular UK association was purely on this basis.”
Ms Mehra, a civil engineer, was appointed to the Grenfell Tower inquiry panel shortly before Christmas, replacing academic Professor Nabeel Hamdi.
It has since emerged that Ms Mehra is an immediate past president of the Women’s Engineering Society (WES), which previously received funding from the Arconic Foundation for an apprentice conference.
Earlier, Karim Mussilhy, vice-chairman of the survivors and bereaved group Grenfell United, told the Guardian: “Her society has been supported by Arconic. She will look at it from the perspective of Arconic doing good things for the industry, that they are a great organisation. Her perspective will be affected.”
However, a spokeswoman for the inquiry said they do not believe Ms Mehra’s former role with the WES will have any influence on her ability to be impartial.
“The consideration and appointment of panel members is a matter for the Cabinet Office,” said the spokeswoman.
“The inquiry does not consider that Benita Mehra’s former presidency of the Women’s Engineering Society in any way affects her impartiality as a panel member.”
A Cabinet Office spokesman said: “There are robust processes in place to ensure the Grenfell Tower Inquiry remains independent and that any potential conflicts of interest are properly considered and managed.”
They added that the Arconic Foundation donated to a “specific scheme which provides mentoring for women in engineering and is unrelated to the issues being considered by the inquiry”.
Downing Street said the prime minister “reaffirmed his commitment to getting to the truth of what happened, learn lessons and deliver justice for victims”.
On Thursday’s meeting with Grenfell families, a No 10 spokesman added: “During the meeting, they reflected on the phase one report of the Grenfell Inquiry, and looked ahead to the next stage.”
Ms Mehra stepped in for the second phase of the inquiry after Prof Nabeel Hamdi, a housing expert, decided to quit because of the commitment involved in taking part in the inquiry.
The second phase of the Grenfell Tower Inquiry begins on 27 January.
After considering the night of the fire, during the first phase, the focus will switch to the refurbishment of the building and its role in the fire, as well as issues surrounding the building regulations.
Thouria Istephan, who specialises in construction regulations, will join Sir Martin and Ms Mehra on the panel.