The under-pressure senator broke his silence over the Chinese payments issue, admitting 22 times he had made a "mistake" by allowing his legal and travel bills to be picked up by Chinese donors - rather than paying the bills himself.

But a visibly chastened Senator Dastyari, who began his "ask me anything" press conference by declaring he was in "no rush", wrapped up questions after just 25 minutes and failed to answer one key question - why he had asked donor Top Education to pay a travel debt.

He later told Fairfax Media that he asked Top Education donor to pay his travel bill "to avoid paying a $1670 bill myself. It was wrong and a big mistake."

As Prime Minister Malcolm Turnbull and his senior ministers called on Senator Dastyari to resign, or for Mr Shorten to axe him, Senator Dastyari emerged from a media black-out to face questions about a Chinese government-linked donor paying his $1670 debt, revelations he had adopted a pro-China stance on the South China Sea dispute at odds with ALP policy and about a $5000 bill he had incurred while general secretary of the NSW ALP picked up by a donor.

On the South China Sea issue, he re-stated his support for Labor Party policy over freedom of navigation exercises in the South China Sea, and suggested he may have been misquoted in Chinese media reports.

The NSW Senator has regularly quizzed senior Defence and Foreign Affairs department officials about Australia's stance over the South China and East China Sea disputes.

In February 2014, for example, he suggested to then-DFAT secretary Peter Varghese that the Australia-China relationship had been put at risk because Australia had sided with Japan and the United States in issuing a communique over the East China Sea.

"How are you able to categorise the current foreign policy relationship between Australia and China is strong?"

Mr Varghese replied that Australia's position had not changed on the dispute and that "I do not have the view that when you disagree with a country that you are putting the relationship at risk. I do not believe China has that view at all."

During his press conference, he described the travel bill was just an "office overspend" and that "I should have paid it myself. I didn't. I regret that and I'm not here to kind of justify or make excuses for it.

"I take no solace in the fact that it was technically within the rules and it was. I should never have asked them to do that. I should have made the payment myself and I should have reflected on that before doing so."

The senator admitted he had been strongly counselled by Labor leader Bill Shorten but had not been asked for his resignation from the frontbench, or from his job as manager of opposition business in the Senate.

Some in Labor have begun discussing whether the Senator may have to step aside for the good of the party.

But Mr Shorten is firmly backing the NSW senator and attempted to shift focus on Tuesday to political donations reform, writing to Prime Minister Malcolm Turnbull and asking for bipartisan cooperation on reform.

He described Mr Dastyari as a "junior" senator several times – despite his senior positions and the fact that he topped Labor's Senate ticket in NSW at the last election.

"Sam Dastyari . . . is a bright young man...he's made an imprudent decision and he acknowledges that and he recognises the mistake he's made," he said.

"In terms of the mistakes that he's made, he acknowledges them but . . . Mr Turnbull here is ducking the real issue . . . What is appropriate in terms of a donation and from whom is it appropriate to receive that donation? Mr Turnbull's got to stop ducking the real issue."

But speaking in China, Mr Turnbull said Mr Shorten was "seeking to distract attention from the very real issue; the very real failure of his leadership in not removing Sam Dastyari from the frontbench".

"Mr Dastyari did not receive a donation for the Labor Party – he may well have done that as well – he took cash for himself. Then he expressed views on foreign policy which were utterly at odds with the established, consistent foreign policy of the Australian government, which is supported by Mr Shorten.

Treasurer Scott Morrison said bluntly that "Shanghai Sam" should resign.

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