US whistleblower Chelsea Manning could be denied entry into Australia by the federal government just days before she’s expected to arrive.

Ms Manning, a former US army intelligence analyst best-known for leaking classified military and diplomatic documents to WikiLeaks, was scheduled to start her Australian speaking tour at the Sydney Opera House on September 2.

However, the federal government is reportedly considering refusing entry to Ms Manning – who was released from military prison in 2017.

The Australian organiser of her speaking tour, Think Inc, has written to supporters asking them to lobby the newly installed Immigration Minister, David Coleman.

“We have just received a Notice of Intention to Consider Refusal under s501 of the Migration Act from the Australian government in regards to Chelsea’s Visa,” the company’s director Suzi Jamil wrote to supporters.

“We are looking for support from relevant national bodies or individuals, especially politicians who can support Chelsea’s entry into Australia.

“We are seeking letters of support to send to the Minister for Immigration in order for him to reconsider his decision.”

"There’s this notion of morality and this notion of legality and they do not always align, often they’re in conflict with each other,” activist and convicted US whistleblower Chelsea Manning @xychelsea says ahead of her visit to Australia on #MatterOfFactABC @StanGrantMOF pic.twitter.com/ALVHPKbvsc

— ABC News (@abcnews) August 28, 2018

Section 501 of the Migration Act allows the Department of Home Affairs and its minister Peter Dutton powers to deny anyone a visa if they do not pass “the character test”.

Amnesty International threw its support behind the visit.

“Amnesty International is very concerned that the Australian government is seeking to silence American activist Chelsea Manning by intending to deny her a visa into Australia,” Amnesty national director Claire Mallinson said in a statement Thursday.

“By refusing her entry, the Australian government would send a chilling message that freedom of speech is not valued by our government. It is not too late for the Government to change their mind,” Ms Mallinson said.

The Department of Home Affairs  refused to comment on individual cases but a spokesman said all non-citizens need to meet certain character requirements before being granted entry.

“A person can fail the character test for a number of reasons, including but not limited to where a non-citizen has a substantial criminal record or where their conduct represents a risk to the Australian community,” the spokesman told ABC.

The transgender activist was also planning on a New Zealand tour which is also threatened to be cancelled.

In 2017, she was banned entry to Canada, but was given permission to speak at an event earlier this year.

Ms Manning was sentenced to 35 years prison in 2010 for leaking 700,000 documents to WikiLeaks in 2010 — the biggest breach of classified data in the history of the US.

However, Greg Barns, a lawyer for Wikileaks founder Julian Assange, said refusing her entry was extraordinary given her sentence had been commuted.

“There have been in the past many people who’ve come to Australia with criminal records … and she should be no exception,” Mr Barns said.

“I don’t think anyone would seriously suggest Chelsea Manning while in Australia would be rummaging through the files of the Department of Foreign Affairs and Trade or Defence or the US Embassy.

“Those provisions are really designed to be utilised in cases where there is a risk that a person may commit offences, is a risk to the Australian community, no one would seriously suggest that’s the case here.”

Ms Jamil said Ms Manning was “so far from a risk to the Australian public”.

“In January 2017, the incumbent President Obama commuted Chelsea’s sentence. That should be a consideration in this instance,” Ms Jamil said.

“We’re still really positive about the whole situation and we want to do everything in our power that we legally can in order to provide the reasoning behind why Chelsea should be able to enter our country.”

-with ABC