LONDON (Reuters) - BHP Billiton , the world's biggest miner, could be dragged into a geopolitical independence row on Monday as a result of its hostile takeover bid for Potash Corp , the Independent on Sunday reported.

The relationship between Canada's Potash Corp and Morocco's state phosphates company, OCP, has led the Sahrawi people, who are fighting for the independence of the Moroccan-occupied Western Sahara, to accuse Potash Corp of propping up an "illegal regime," the paper reported.

Western Sahara Resource Watch (WSRW), an activist group, will write to BHP's management and shareholders on Monday to urge them to reconsider their possible involvement.

OCP is estimated to supply about 500,000 tons of phosphates to Potash Corp, the paper reported.

Elsewhere, the Sunday Times reported that Potash Corp is seeking help from China's Sinochem Group to fight off BHP's hostile $39 billion offer.

Sinochem, China's biggest chemical trader and top fertilizer firm, is the parent company of Sinofert <0297.HK>, in which Potash owns a 22 percent stake.

Sinofert is considered the most logical candidate to lead a counter offer, industry sources have said.

Sinochem is unlikely to make an outright takeover given the national importance of Potash Corp, but it could buy a large minority stake, the Sunday Times said.

Other takeover targets have tried to use a similar defense. Two years ago, at the height of BHP's hostile takeover attempt for Rio Tinto , China's state-back Chinalco bought a 9 percent stake in Rio, a purchase meant to help block the deal.

(Reporting by Julie Crust; Editing by Jon Loades-Carter)