Junior minister's 'missing senator alert'

The minister assisting Malcolm Turnbull has facetiously urged Labor to release frontbencher Sam Dastyari to answer questions over controversial Chinese donations.

Assistant minister to the prime minister James McGrath called on Labor to "untie, unburden and un-gag" Senator Dastyari, who he says is also known as "no need for a cheque I have my own Eftpos machine".

"It has come to my attention that Senator Sam Dastyari... is missing presumed locked-up in Bill Shorten's filing cabinet," his Facebook post titled "Missing Senator Alert" said on Monday.

"The media are slowly dying without their hourly updates from Sam on his latest political machinations."

Senator Dastyari is under fire for accepting cash from a Chinese donor for personal debts, not declaring wine gifts and for offering Chinese media a seemingly different stance to Labor policy on territory claims in the South China Sea.

The opposition leader is resisting growing pressure from government ministers to sack Senator Dastyari - who usually makes himself readily available for media comment.

Senator McGrath's appointed nickname follows other name-calling by senior government figures including "sky-rocket Sam" and "Shanghai Sam".