By Azizullah Khan BBC correspondent in Quetta

Over the border Afghan heroin production has increased

About 1,000 officials are taking part in the operation in the Gulistan and Inayatullah Karaiz areas, 100 kilometres (60 miles) north of Quetta, near the Afghan border.

Many farmers have held protests, saying opium cultivation - used in heroin and other drugs - is their only means of making a living.

In February, the UN's drugs monitoring body said it was concerned about a resurgence in poppy cultivation in Pakistan and neighbouring Afghanistan.

First time

The director of Pakistan's anti-narcotic force, Liaqat Ali Toor, told the Daily Times newspaper detailed meetings had been held with local people to win their permission to destroy the poppy fields.

He said the crop had been cultivated for the first time in Balochistan last year and that officials had only discovered it this year.

Mr Toor said all efforts would be made to eradicate poppies throughout Balochistan, where the crop has been farmed in about 1,500 acres.

Meanwhile, angry farmers in Qila Abdullah district blocked roads leading to Afghanistan for several hours on Thursday.

They say a long drought in the area and soaring taxes have hit them hard.

One local farmer, Gul Agha, said they had grown nothing for five years and had lost fields and orchards because of the dry weather.

He said government officials had ignored the area.

Farmers have struggled with other crops

"Presently we are compelled to beg," said Mr Agha.

Others support the steps taken by the government, but say the farmers must be given help with alternative sources of income.