CLAW Constructions owner Troy Armstrong says he was warned by CFMEU organiser Tony Vitler in 2012 that he would not win jobs if he didn't sign an enterprise bargaining agreement with the union, or alternatively, make donations or sign-up members.

"I took this to mean they were leaning towards wanting a bribe," Mr Armstrong said in his witness statement to the royal commission into trade union corruption.

During a meeting at a McDonalds outlet in Fyshwick, Mr Armstrong said Mr Vitler told him the union could guarantee him work if he signed an EBA with them.

"We make sure IC and Pacific take the big jobs in town and we will make sure the little jobs go to you," Mr Vitler allegedly said.

When Mr Armstrong told Mr Vitler he could not afford to pay the labourer rates within the EBA, he replied: "I don't give a f*** about small businesses".

 "He definitely threatened to kick me off sites if I did not sign an EBA," Mr Armstrong told a hearing of the commission in Canberra on Monday.

Numerous worksites were disrupted by the CFMEU over safety concerns soon after his refusal to sign the EBA.

"As a result of not signing EBA's ... I believe I have missed out on a number of jobs and have been subjected to an unfair level of scrutiny on sites as payback."

"I never want to sign an EBA with the CFMEU or anything else because they are liars, thugs and not worried about safety. 

"They just use the safety as a method of blackmailing business and people to sign up with them."

Mr Armstrong denied accusations from the union's lawyer John Agius that he was "anti-union", rejecting calls to withdraw claims of bribery and blackmail.

"I suggest that (Mr Vitler) never said anything to you that would make you believe that he was inferring a bribe," Mr Agius said.

"I believe he did," Mr Armstrong replied.