Cabinet minister Christopher Pyne has been forced to backtrack after claiming Labor powerbroker Sam Dastyari broke the rules over gifts and donations from Chinese business interests, while also refusing to say what the government would do to address growing concern over Australia's donations system.

The NSW Labor senator is under siege after Fairfax Media last week revealed he had a Chinese government-linked donor pay a $1600 debt and that he had adopted a pro-China stance on the South China Sea dispute.

Mr Pyne told ABC radio there was more to the story than the travel bill, asserting that "the seduction of Sam Dastyari has obviously been going on for some time".

"Chinese business interests paid a $40,000 legal bill for Sam Dastyari, a $1600 travel bill, provided him with two bottles of Grange wine and after all these brandishments, Senator Sam Dastyari was prepared to say that the South China Sea was China's business and that Australia should remain neutral, a position which is at odds with Labor's policy, the national interest and with our international interest," he said.