The company, whose brands include Dove soap and Lipton tea, is one of a number of multinationals named in a damning report on underage employment in India's huge cotton seed industry.

Unilever, which says it is strongly opposed to child labour, has agreed to meet campaigners to discuss the issue.

A spokeswoman told BBC News Online the company was surprised to find itself at the centre of the allegations.

"We will discuss the options and wishes of the NGOs [non-governmental organisations] at the meeting," Alexandra Middendorp said, but could not confirm a date for talks.

Chocolate 'bribes'

The report, published by the India Committee of the Netherlands, said Unilever buys hybrid cotton seeds from farmers who pay children a handful of rupees to work long hours in hazardous conditions.

It said about 90% of all labour in the Indian cotton seed market was carried out by 450,000 children, some of them as young as six and most of them girls.

"These girls work long days, are paid very little, are deprived of an education and are exposed for long periods to dangerous agricultural chemicals," the report said.

It accused farmers of securing the girls' long-term labour by offering their parents loans, which took months or years to repay.

The report said children were offered biscuits, chocolate and other inducements to encourage them to work harder.

Puberty myth

Narasamma, 12, told the report's authors she had worked in the cotton fields for the last five years.

She sleeps in a cattle shed, and works more than 13 hours a day, with two breaks.

For that she is paid 30 rupees, less than $1 a day. The average child wage on a cotton farm is 18 rupees.

Bonded or tied labour is a particular problem in Andhra Pradesh state, where much of the report's research was carried out.

Underage workers are particularly prevalent in cotton-growing districts of the state, where there are large numbers of landless poor who cannot afford for their children to go to school.

Joseph Ghattia, the head of India's Centre of Concern for Child Labour, says the high percentage of young girls employed in the hybrid cotton industry is not just a matter of economics.

The farmers, he said, encouraged people to believe that cross-pollination would only work if it was carried out by girls who had not yet reached puberty.

"It's a cruel practice of putting this in the minds of the people," Mr Ghattia told BBC News Online.

Unilever 'willing to talk' Working in India's hybrid cotton industry is extremely labour-intensive - each individual cotton flower bud has to be delicately pollinated by hand.

The process by which the cotton seeds are purchased is almost as complicated.

Unilever buys the seeds through its subsidiary, Hindustan Lever, from a company called Paras Extra Growth Seed.

Paras Extra Growth Seed, in which Hindustan Lever has a minority stake, buys the cotton seeds from middlemen known as seed organisers, who in turn buy the seeds from farmers.

Farms are responsible for employing the children - but campaigners point out that the amount the farmers receive for the seeds has an impact on wage levels.

Unilever says it does not accept direct responsibility for employing the children. It would not disclose to BBC News Online any ideas it has to help.

But the company says it has always shown its willingness to discuss the issue of child labour.

Human rights

The India Committee of the Netherlands says attempts to get Unilever to sit down and talk have so far failed.

It says a promised meeting between Hindustan Lever and a prominent Indian child rights group, the MV Foundation, also never took place.

"We hope we can fix a meeting by 15 May to see if we can really make some progress," Gerard Oonk, the India Committee's coordinator, told BBC News Online.

He said Unilever was first informed about the child labour issue in the cotton industry a year ago.

Human rights group Amnesty International said: "The reported conditions clearly raise concerns - particularly on health grounds and the right of children to education.

"It is essential that companies recognise their full responsibility for the human rights of all involved in their supply chains."