By Crispin Thorold BBC correspondent in Kabul

The Afghan government is hoping to wean farmers off poppy crops

Around 1,000 farmers demonstrated near a provincial capital, Jalalabad.

They say they have not been adequately compensated for the destruction of their poppy crops.

In recent months, counter-narcotic officials have warned that opium production in Afghanistan will be the highest it has been for years.

Afghanistan is the source of the majority of the world's heroin.

Opium which is used to produce heroin was virtually eliminated by the Taleban but production is now flourishing.

This year, the yield is expected to be 20% higher than last.

In recent weeks, there have been several government raids.

The opium farmers protesting in the eastern Afghan province, Nangarhar, say they have received little compensation for the destruction of their fields.

For many, cultivating poppies is the only way to provide for their families, from land where little else will grow.

Lucrative business

Afghan President Hamid Karzai acknowledges that as his government attempts to eradicate opium farmers must be dealt with in a different way to the military commanders who profit from the drugs trade.

"We have a plan to distinguish between the warlords that are cultivating lands with poppies and the poor farmers. The plan of destruction is taking this into account," he said.

"Poppy production goes against nation-building. It goes against the building of institutions in Afghanistan. We must rid this country of poppies."

But this illicit business generates over $2bn annually, in a country with few other sources of income.

Last week, the international community pledged billions of dollars to Afghanistan over the next three years.