But Greens leader Shane Rattenbury says he has seen "no real evidence" to support their "extraordinary claims".

The Canberra Liberals on Wednesday gave notice of a motion of no confidence in Chief Minister Andrew Barr, citing Labor's relationship with the unions and controversial land deals in Dickson and Glebe Park as proof of "corruption".

The Dickson land swap deal will be the subject of an ACT Auditor-General probe.

Asked why the Liberals did not wait for the findings of that investigation to be released, Mr Coe said "there is no doubt in our minds there is corruption taking place in Canberra".

Mr Coe said his team were still compiling evidence to support his allegations, which would be released over the coming week and debated in the Assembly next week.

But Mr Rattenbury said the motion was a "stunt" given the Opposition was still gathering evidence to back up their claims.

"To describe Canberra as the corrupt capital of Australia is an extraordinarily broad claim that is not backed up by the evidence we've seen and that's not to say there aren't issues in this town and that's why we support the establishment of an anti-corruption watchdog, it's right to have that mechanism but to make such a broad and sweeping claim is really an overstatement and a political tactic," Mr Rattenbury said.

Mr Coe accused the Greens of "overlooking integrity" because of their "tight coalition" with Labor.

"I am very confident the information we're exposing and information we're demonstrating is clear evidence of a lack of integrity and it warrants no confidence in this government," Mr Coe said.

"The challenge is going to be for the Greens and for the Labor party members as to whether they accept that this is business as usual in Canberra or are they going to say enough is enough."

On ABC Radio on Thursday morning, Mr Coe said he had forwarded some information related to the allegations to police.

Upon later questioning, Mr Coe revealed the information he was referring to was the "manipulation" of his freedom of information request by the Land Development Agency in 2015.

Mr Coe said he had not referred any other allegations to police at this point.

Unions ACT secretary Alex White challenged Mr Coe to repeat his allegations outside the ACT Legislative Assembly, which he dubbed the "cowards castle", or resign.

He said the Liberals were "overreaching everywhere", referencing Senator Michaelia Cash's staffer tipping off media before an Australian Federal Police raid on the Australian WOrkers' Union headquarters on Tuesday.

"This is an unacceptable use of parliamentary privilege," Mr White told Fairfax Media.

"[Mr Coe] is abusing his position in the Assembly, and misusing parliament privilege to make unsubstantiated and defamatory allegations about individual officeholders in the unions."

The motion comes days after Liberals politician Andrew Wall accused the unions of stopping Labor MLAs from attending a Master Builders Association ACT awards dinner last Thursday.

Mr Barr emphatically denied that was the case and his spokesman said: "MLAs get lots of invitations and cannot accept them all."

Backbenchers Chris Steel and Tara Cheyne, and Attorney-General Gordon Ramsay were at a National Gallery of Australia launch, according to a tweet from Mr Steel.

Mr White would not confirm or deny the accusation but admitted volunteers were at the event handing out leaflets about the construction body's "safety record".