Meanwhile, department secretary Michael Pezzullo told a forum this week he could not discuss the proposed new headquarters, lest his comments be seen to breach the impartiality of the decision.

The possibility of about 4000 Immigration staff leaving Belconnen has panicked the town centre's shopkeepers, who say the department is the engine of Belconnen's economy.

Mr Pezzullo is overseeing the merger of the Immigration Department and the Australian Customs and Border Protection Service, which has about 1500 staff in Civic.

The two agencies' building leases begin to expire from late 2017, and Mr Pezzullo

The department invited developers to bid to build or refit an office that suited its needs, and was scheduled to select the winning tender at the beginning of March.

However, asked about the delay, a spokeswoman said on Thursday: "To date, the evaluation process is yet to be finalised and no further information is available at this time."

Earlier this week, Florey resident Kim Fischer, who has worked with ACT Labor ministers and is "considering" running for preselection for next year's election, confronted Mr Pezzullo after he gave a public lecture at the Australian National University.

"As unelected public servants, what gives you the right to decide that 4000 Immigration workers should move out of Belconnen, destroying local businesses and causing traffic chaos to the ACT?" she asked.

Mr Pezzullo said the decision was being made in line with Commonwealth procurement policies and he had to take care in what he said.

"We

It's not fair to the parties who put forward propositions for the purposes of that tender evaluation.

"It would be a breach of probity for me to speculate on that."

Ms Fischer said Immigration Department staff had told her "they're afraid of the repercussions if they tell management they don't want to move".

"I've handed out petitions at the bus interchange and they say are they too scared to sign because they fear for their jobs," she said on Thursday.