Incoming foreign minister Julie Bishop has already clashed with her department over luxury hotel accommodation on an upcoming trip to New York.

The minister-elect told Department of Foreign Affairs and Trade bureaucrats to slash the cost of the trip after they planned to book $1850-a-night rooms at a swish Manhattan hotel for an entourage of dozens.

Cutting costs: Julie Bishop. Credit:Pamela Mirghani

Ms Bishop also instructed DFAT not to book her on first-class flights when she travels overseas in her new brief.

It is understood departmental bosses want to take a delegation of 23 public servants to the United Nations leaders' summit on September 19-20 along with two ministers and three of their staff with the travelling party staying at the four-star Westin Midtown Hotel. The department planned to put Ms Bishop and her colleagues in a suite at the Westin as part of an accommodation package worth $132,048.