Age UK has written to the UK’s major banks and building societies asking them to set out what steps they are taking to ensure cheques do not "wither away".
It said they would be available "for as long as customers need them".
The news was welcomed by charities, which feared the abolition of cheques would lead to a fall in donations.
But Age UK said in a statement yesterday that cheques were still at risk and that banks and building societies needed to explain how they planned to restore confidence in them.
"We need to know there are definite plans in place to restore trust in them," said Michelle Mitchell, Age UK’s charity director. "Otherwise, cheques will simply be allowed to wither away and their demise will be blamed on lack of demand."
Mitchell said confidence in cheques had been "seriously undermined" by the abolition of cheque guarantee cards in June.
Louise Richards, director of policy and campaigns at the Institute of Fundraising, said it was pleased Age UK had written to the banks.
"I think we have to remain vigilant on this one," she said. "We’ve won the battle but not won the war yet. Banks and building societies are going to make it increasingly difficult to use cheques."