Norwegian Defense Minister Kristin Krohn Devold would be a "very attractive" candidate for the job when Robertson stands down in December -- although a dark horse could yet sneak up to take the post, said one.

Devold, 41, who is credited with pressing through tough defence reforms in her homeland, is in the running with European Commissioner Antonio Vitorino, 46, of Portugal.

"We are down to two names. They are both interesting and credible. She's a very able and attractive person, while he's an exceedingly efficient operator, one of the best commissioners there is," said the senior envoy.

But he added: "If you scratch most of us I think you would find that there is not necessarily a consensus emerging around either," and cast doubt over whether a successor to Robertson will be found before September.

"It may end up as one of these two, but there is a feeling that someone else could suddenly pop up," he added, citing Robertson's nomination in 1999, when he emerged at the last minute after having had a "good war" in Kosovo.

Robertson announced in January that he will stand down in December as head of the world's premier military alliance, sparking a rash of speculation. Other possibles have included Polish President Aleksander Kwasniewski and former Danish prime minister Poul Nyrup Rasmussen.

Italian Defence Minister Antonio Martino had in recent months been tipped as the frontrunner, after reports he had the backing of US President George W. Bush.

But diplomats in Brussels are now dismissing this, with one senior US source saying Bush had "never" publicly expressed a preference and another envoy saying Martino's EU views had raised a number of European eyebrows.

Speculation about Vitorino's prospects was fueled Wednesday by reports that he was due to hold talks with US Defense Secretary Donald Rumsfeld during a meeting of NATO ministers starting Thursday in Brussels.

But a US official refused to be drawn, saying only that Rumsfeld was meeting "a broad range of people" -- although he stressed that finding a successor to Robertson was a key priority.

But he said: "It is a very mysterious process, a bit like choosing a pope. When the smoke appears from the chimney we will tell you."

WAR.WIRE