Revelations that Labor's Sam Dastyari told a Chinese benefactor his phone was most likely being tapped by intelligence agencies makes his position in the Senate "untenable", the Turnbull government says.

Foreign Affairs Minister Julie Bishop has accused Senator Dastyari of acting against Australia's national security interests and Attorney-General George Brandis said the revelations raised serious questions about his loyalties.

Senator Brandis said the revelations were also a test for Opposition Leader Bill Shorten, who brought Senator Dastyari in from the cold by giving him the leadership role of deputy Senate whip earlier this year.

Mr Shorten said while he receives regular confidential briefings from security agencies in his role as a major party leader, he denied sharing any of that information.