Compensating women who believe they lost out financially due to state pension age changes will be expensive but there is a need to right the "injustice", says Labour's John McDonnell.
The shadow chancellor made his comments to Sky News' Sophy Ridge on Sunday programme as the party pledged, if it wins the election, to make payouts to those affected, which could total £58bn over five years.
Nearly four million women born in the 1950s have been affected by the change to raise the state pension age from 60 to 66 in a move to ensure "pension age equalisation".
Women Against State Pension Injustice (WASPI) campaigners argue they were given insufficient time to prepare for the reform brought in by the former coalition government.
Boris Johnson was challenged by one of the women in the studio audience for Friday night's BBC Question Time special.
The prime minister said that while he sympathised deeply, he could not promise to "magic up that money" for them.
Under the Labour plan individual payments would average £15,380 with a maximum payout of £31,300.
Mr McDonnell said Labour had been working on a settlement for 18 months, although it did not feature in the party's manifesto or the accompanying costings.
The eye-catching move comes on the same day as the Conservatives launch their manifesto.
Mr McDonnell told Ridge: "These are the 50s women who paid into their national insurance, expected to be retiring at 60 and then legislation was introduced to extend their retirement age and they weren't properly informed.
"We need something in place to redress this injustice."
Acknowledging it was "expensive", he added: "This is an entitlement, this is not a benefit. This is a historical injustice we have to redress it.
"Some of these women have been forced into penury and they were given no adequate notice. They were not properly informed and it has caused real hardship.
"If we don't do it now, some of them will no longer be with us."
The Brexit Election on Sky News - the fastest results and in-depth analysis on mobile, TV and radio.