The move would double the amount of time father receive and encourage them to spend more time with their newborns, according to an influential think-tank.
The Institute for Public Policy Research (IPPR) has suggested fathers could automatically be given four weeks off work after the birth, paid at the minimum wage. Under its proposals the state would pay, but employers would be encouraged to make up the difference to a workers' normal salary.
The IPPR estimates the policy would cost the Treasury about £150 million a year.
Labour said it was considering the "very interesting proposal", but party sources insisted it would not "make unfunded spending commitments".
Conservative skills minister Matthew Hancock condemned the idea of four weeks' leave as unaffordable, adding: "This policy would mean even more spending, more borrowing and more taxes - exactly what got us into a mess in the first place."
Kayte Lawton, from IPPR, said: "Fathers' greater involvement in family life can make it easier for mothers to return to work after taking maternity leave, which helps to raise the family's income and lessen the impact of motherhood on women's careers."