Opium poppy cultivation in Afghanistan is expected to increase for a third straight year, expanding even to poppy-free areas this year, a United Nations report warned on Monday.

The Afghanistan Opium Risk Assessment 2013 said Afghanistan was moving towards record levels of opium production this year despite eradication efforts by the international community and Afghan government.

"The assessment suggests that poppy cultivation is not only expected to expand in areas where it already existed in 2012... but also in new areas or in areas where poppy cultivation was stopped," the survey said.

The study by the United Nations Office of Drugs and Crime (UNODC) says that a strong association between insecurity, lack of agricultural assistance and opium cultivation are fuelling the trend.

"Villages with a low level of security and those which had not received agricultural assistance in the previous year were significantly more likely to grow poppy in 2013," the report said.

Twelve provinces are likely to show an increase in opium cultivation, while three provinces formerly free of poppy are at risk if eradication is not implemented, it said.

Cultivation is mostly increasing in southern provinces where the Taliban are more active and thousands of international troops are set to withdraw this year.

Afghanistan produces about 90 percent of the world's opium and in 2012 the UNODC warned that opium cultivation in the country had increased by 18 percent.

Last month, Afghanistan said it planned to destroy 15,000 hectares (37,000 acres) of poppy fields this year in its latest efforts to control the heroin trade that fuels endemic violence and corruption.

Poppy farmers are taxed by Taliban militants who use the cash to help fund their insurgency against the government and NATO forces, according to the UNODC.

The poppies, which provide huge profits in one of the world's poorest countries, also play a large part in the corruption that plagues Afghan life at every level from district to national government.