Bridge House Trust suspended its Access to Buildings grants programme in August and Lloyds TSB Foundation for England and Wales altered its grants stream earlier this year.
Both grant-makers believed they would not be able to make money available for such building work because it became a statutory requirement for charities to provide disabled access from 1 October, when part three of the Act came into effect (Third Sector, 17 November).
But Caroline Gooding, special adviser to the Disability Rights Commission, wrote to both grant-givers after reading Third Sector's story to inform them otherwise.
In her letter, she said the Act requires service providers to make physical adjustments to improve disabled access "only where it is reasonable for them to do so". Gooding added: "One of the key determinants of 'reasonableness' is the availability of funds."
She said it would not be reasonable for charities with restricted funds to incur significant expenditure to carry out building work and few charities would be under a statutory duty to improve access for disabled people.
"I think trusts want to preserve their funds so that they are not wasting money on paying voluntary organisations for what those organisations would otherwise be required to do legally," said Gooding. "But charities with small funds won't be legally required to make these changes if trusts do not fund them.
"It would be a ludicrous situation if passing a law to improve access means funds become less available as a result."
Gooding is seeking a meeting with the Charity Commission to clarify the legal position.