Justice Shane Marshall ordered that Australian Manufacturing Workers Union organiser Tony Mavromatis and his union be restrained from stopping access to the City West Water project in Werribee.

Mr Mavromatis has been accused of being behind protests on the site and trying to force a contractor to sack four Filipino workers engaged on 457 work visas.

Justice Marshall said there was a ''serious question to be tried'', with the next hearing on March 6.

The union faces hefty fines if it loses the case, with losses to contractors already estimated at more than $1.5 million.

But the orders - which will be in place until March 6 - are limited and Justice Marshall said they would not stop the protests at the site by a group of unemployed workers. The ''central issue'' was whether Mr Mavromatis was behind the protest, which he denies.

There was speculation that police may try move the protesters as early as Friday, and the head contractor at the site, Tedra Australia, said it ''looks forward to being able to access its worksite in the very near future''.

A police spokesman said they were ''working closely with all parties involved to assist in a resolution''.

Justice Marshall was critical of some of the tactics of industrial relations consultant Grace Collier, warning she may have broken the law.

Ms Collier, an Australian Financial Review columnist, used listening devices - including in her bra - to record Mr Mavromatis.

Justice Marshall said a recording she did on a computer ''raises a serious concern as to whether she had breached the provisions of the Telecommunications [Interception and Access] Act''. He said without precise detail on what occurred, ''the court is unable, at present, to say any more about that matter''.

Earlier in the week Justice Marshall said Ms Collier had engaged in ''James Bond''-style antics.

The AMWU denies any involvement with the protest.