New legislation has come into force which allows fathers to take 13 weeks unpaid paternity leave during the first five years of their child's life.

The law applies to the parents of children born from 15 December. It could help up to one million people, the government says.

The law forms part of the 1999 Employment Relations Act.

It has been welcomed by parents while businesses fear the extra leave could cost them money. But some parents say they will not be able to afford to take very much unpaid leave.

Fathers will be allowed to take time off at the birth or adoption, providing they give three weeks notice to their employer.

Under the new law, mothers are set to get an extra four weeks guaranteed maternity leave, giving them a total of 18 weeks.

Adrienne Burgess, co-founder of Fathers Direct welcomed the news. "We know there are still men being sacked for taking time off to spend with the family, so it's good news. It is a symbolic step forward. For the first time, fathers are being recognised as an equal partner in the family," he said.

Baby boom

Father of one Roger James is expecting a second child in April next year.

"Our lives changed completely," Mr James said of the birth of his daughter, Ruby. "Seven days later, you are back at work, you are cutting off that experience before you should. It is slightly alienating. Next time I would like to be able to take two weeks of unpaid leave around the birth. It is the most stressful time."

Under the new measures, both parents are allowed time off for family emergencies.

"It has caused friction on at least one occasion because even the most understanding of bosses do not see it a right," Mr James added.

But some fear that the extra leave - even though it is unpaid - will hurt small businesses.

British Chambers of Commerce Dr Ian Peters, deputy director general, said:"We think it could cost firms revenue and even jobs. It is a barrier to competitiveness and a further thorn in the side of small businesses."

More than half of the businesses asked in a recent survey said that two weeks was the longest amount of time that a firm could cover for an absent worker without needing a replacement.

While the government suggests workers are to take between one and four weeks each year, the BCC says this could be negotiable. One alternative is if employees work one hour less a day.

These fears are largely dismissed by unions, who also welcome the move.

"The same things were said about maternity leave and the minimum wage," Dave Prentis, deputy general secretary of Unison said. "If workers work for the kind of firm that has these family friendly policies, it is an incentive to stay where they are.