Businesses clashed with leading infertility charities yesterday over the right to time off work for fertility treatment.

With some women taking several weeks off for treatment, as well as annual holiday, paid leave for treatment was condemned as "dangerous for business" by leading think-tanks.

But FTSE100 companies and businesses across the United Kingdom will receive fact sheets from the Infertility Network, urging them to give sick leave for fertility treatment.

Asda, Barclays and London & Quadrant Housing Group already offer paid leave for women having the treatment. Boots has a policy that staff "may" be eligible, while other businesses, including Barnet Homes, are investigating whether to grant special leave. Sally Jacobson, the human resources director of Quadrant Housing, said: "We give no limit on the number of attempts that will be granted as paid leave, because we want to make the treatment as stress-free as possible. We would urge other employers to do the same. It engenders goodwill and loyalty."

Clare Brown, chief executive of the Infertility Network, said: "There should be a policy in companies that needing fertility treatment is regarded as an illness. We would like all companies to be aware of the physical and emotional impact of treatment."

But the idea of businesses giving paid fertility leave was condemned as "crackers" by Ruth Lea, the director of the Centre for Policy Studies. She said: "How can we compete if we are paying for people's lifestyle choices with business picking up the bills?"