The Prime Minister's neither opening nor closing doors on who may be the country's Foreign Minister after the next election.

Bill English has been asked as to the chances of New Zealand First Leader Winston Peters getting the job after this year's election.

Mr Peters is a vocal opponent of free trade deals - the question's come up as Mr English is trying to promote FTAs on his trip to the UK and Europe.

Mr English said he doesn't want to pre-judge what might happen.

"not ruling anything in, not ruling anything out. I'm not going to speculate on ministerial appointments after an election that's still some time away."