BRUSSELS The war in Ukraine will increasingly be a battle between large numbers of poorly trained Russian troops with outdated equipment and a smaller Ukrainian force with better Western weapons and training, NATO's top military official said on Wednesday.

Admiral Rob Bauer, the chair of NATO's military committee, noted Russia was now deploying significant numbers of T-54 tanks - an old model designed in the years after World War Two.

"But the problem is they still have a lot of T-54s. So ... in terms of numbers, quantity, it is an issue," Bauer told reporters after a meeting of the alliance's national military chiefs at NATO headquarters in Brussels.

"What we will see now is that the Russians will focus - have to focus - on quantity, larger number of conscripts, and mobilize people, not well-trained, older materiel. But large numbers," he said.

The Ukrainians meanwhile would "focus on quality, with Western weapon systems and Western training. That's the big difference in the coming months, I would say."

Bauer said the NATO military chiefs restated "unrelenting support" to a Ukrainian representative at the meeting.

"There is no doubt that NATO will support Ukraine for as long as it takes," said Bauer, a Dutch military officer.

U.S. Army General Christopher Cavoli, NATO's top commander for Europe, added the degradation of Russian forces was "very uneven".

"It's predominantly in the ground forces," he said.

(Reporting by Andrew Gray; Editing by Alex Richardson)