The government has been warned that postponing the extension of flexible working rights would be "misguided" and "a really big mistake".
Speaking before the Business and Enterprise Committee, Mandelson said: "If the British Chambers of Commerce or the [manufacturers' body] EEF say to me these proposals for regulation are going to be onerous in the current economic climate, and can we postpone them for a year or more, then I will consider that."
The Chartered Institute of Personnel and Development (CIPD) and women-in-work campaign group Opportunity Now slammed the announcement.
Mike Emmott, employee relations adviser at the CIPD, said delaying flexible working legislation would send out the wrong signal to businesses.
"It would be misguided to postpone legislation on the spurious ground that it is a burden to business," he told Personnel Today.
The government's own research on flexible working showed it could improve productivity, as well as reducing staff turnover and absenteeism
Helen Wells, spokeswoman on flexible working at Opportunity Now, said: "To postpone the extension would be a really big mistake. It would send out the message that flexibility is difficult and expensive, whereas, if you get it right, it delivers tangible benefits."
The right to request flexible working is set to be extended in April 2009 from those with children up to the age of six, to those with children up to the age of 16.
Mandelson insisted no decision had been made and that he was listening to all sides of the argument.