Selling kidneys from living donors is not illegal in Pakistan, which medical experts say has a reputation as the world's "kidney bazaar".

But police said those arrested in the eastern city of Lahore tricked people then drugged them before removing their kidneys.

"These poor people were given tranquillisers and were deprived of their kidneys without their consent," Lahore police chief Malik Mohammad Iqbal told Reuters.

Hundreds of rich foreigners come to Pakistan every year and buy kidneys from live, impoverished donors, in a business thought to be worth millions of dollars.

Pakistan has no law governing the trade in organs but one is going through parliament aimed at ending their sale.