Embattled Labor Senator Sam Dastyari could be referred to a parliamentary committee over allegations he advanced Chinese interests in Senate estimates hearings in return for payment.

Attorney-General George Brandis will move a motion to refer Senator Dastyari to parliament's privileges committee when the Senate sits in February over what he says appears to be a "very serious breach".

Senate President Scott Ryan says he has received a letter from Senator Brandis concerning payments from companies Yuhu Group and Top Education Institute to settle Senator Dastyari's debts before "echoing" Chinese policy positions through repeated questions in estimates hearings.

Senator Brandis raised this issue after News Corp Australia reported Senator Dastyari levelled 115 questions at senior defence officials that appeared to advance policy positions regarding the South China Sea and Australia's relationship with Japan.

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Senator Dastyari has defended the allegations, saying he was just doing his job by holding officials to account.

Having travel and legal costs paid by the Chinese companies cost Senator Dastyari his position on Labor's front bench last year.

The NSW Labor powerbroker resigned his position as deputy whip in the Senate last week after a recording emerged of him contradicting his party's policy on the South China Sea.

The prime minister has called for Senator Dastyari's resignation over the latest scandal, while Immigration Minister Peter Dutton has labelled him a "double agent".