Quetta, Pakistan — Hundreds of gun-totting farmers angered over the government's destruction of their opium crop blocked a major highway in southwest Pakistan and burned two paramilitary vehicles and a United Nations car, officials said Wednesday.

The poppy fields were destroyed by paramilitary police in an early morning raid, said Colonel Abdul Basit, spokesman for the Frontier Constabulary.

Soon after, farmers armed with assault rifles seized a stretch of highway near the Afghan border. When confronted by paramilitary forces in the area, the farmers forced the officers from two of their four-wheel drive vehicles and torched the jeeps, he said.

The farmers also burned a car that belonged to the UN Family Health Association, although the driver, the only person in the car, was not hurt, Col. Basit said. The UN vehicle was in the area for a polio immunization campaign that began this week.

With the paramilitary forces in the area unable to clear the road 135 kilometres northwest of Quetta, the capital of Baluchistan province, the government sent troops in to restore order, he said.

The farmers dispersed soon after the soldiers arrived, and there were no reports of fighting, Col. Basit said.

The opium poppies were destroyed under a government program to eradicate the plant, which is used to make heroin, he said.

“We took action only when they refused to destroy their crop voluntarily,” Col. Basit said.

Poppy cultivation has been increasing in the remote tribal regions along the border with Afghanistan. The government has little control over the region and opium poppies fetch much higher prices than other crops, such as corn, that the region's farmers might grow.