Authorities say the gang was involved in selling kidneys to international clients, particularly from wealthy Gulf nations.

"A team comprising seven officials raided a house in Lahore and caught four people red-handed illegally transplanting kidneys to two Oman nationals," Jamil Ahmad Mayo, Deputy Director of the Federal Investigation Agency, told AFP.

The two Omanis, who have also been taken into custody, had paid seven million rupees ($70,000) each for a kidney, he said.

Organs can only be donated by close relatives in Pakistan and buying and selling them is illegal.

However, a chronic shortage of organs for transplant has fuelled a black market, with acute poverty forcing some Pakistanis to sell their kidneys to eke out a living.