The Prime Minister has said the Opposition will not be given access to the nation's top public servants until an election is formally announced.

Malcolm Turnbull has written to the Opposition Leader Bill Shorten to respond to his request for pre-election briefings with departmental officials.

In a letter to Mr Turnbull written on Thursday, Mr Shorten argued caretaker provisions should now be in place because the Government had indicated a double dissolution election would be held on July 2.

He cited the Guidelines for Pre-election Consultation and argued Mr Turnbull had "announced" the election in Question Time this week.

Mr Shorten also said he would "shortly contact the Secretary of the Department of the Prime Minister and Cabinet" to arrange a meeting to discuss Opposition policy.

But Mr Turnbull said the Opposition would be denied access to the country's most senior public servants until after an election was called.

"I am, however, happy to indicate that you will be given approval to have discussions with the Secretary of the Department of the Prime Minister and Cabinet at the appropriate time," Mr Turnbull said in the letter.

"As you know, the election cannot take place until His Excellency the Governor-General decides to issue a proclamation dissolving the Parliament.

"His Excellency has not yet done so, nor have I advised His Excellency so to do. The pre-election period has not therefore commenced."

It is likely an election will be called in the days following the May 3 budget.

Mr Turnbull said the Opposition Leader would be able to hold discussions with senior public servants "at the appropriate time".

He also warned Mr Shorten not to contact public servants, such as the secretaries of departments, directly and said this was an "inappropriate procedure".