He said a directive had already been issued to the states and although no deadline was imposed, the authorities should not "sit on the matter".

"We have told the state governments to ensure pig farming is conducted in a controlled and systematic environment to avoid pollution".

"If the farmers refuse to relocate to enable a more efficient farming system, then we suggest that action be taken to close down the farms as this is the only way to prevent further pollution," he told reporters after attending his ministry’s Merdeka Day celebrations here yesterday.

Azmi also warned "irresponsible parties" against using pig farming as a racial issue to gain public support.