"The President of Romania informed... NATO allies that he withdrew his candidacy for the post of secretary general of the organisation," the Supreme Council of National Defence announced, adding that Romania now backed Rutte.

"President Klaus Iohannis asked the members of the council to give their opinion on Mark Rutte's candidacy for the post of NATO Secretary General, and they declared themselves in favour of Romania's support for the Dutch Prime Minister's candidacy."

Iohannis's withdrawal clears the way for Rutte to succeed Jens Stoltenberg as head of the defence alliance later this year as he has gained other allies' support.

The nomination of a new NATO secretary general requires consensus from all 32 alliance members.

Iohannis, 65, had vowed to bring a "renewal of perspective" to the alliance as a member of its eastern flank.

Rutte currently serves in a caretaker capacity as prime minister and is set to leave his position in the coming weeks once a new Dutch government is installed.