A former Royal Air Force chief has said suspected Chinese spy balloons are "an irritation" but "it would be very useful to find out what's actually in them before we get too excited".
Air Chief Marshal Sir Michael Graydon, previously head of the RAF, told Nick Ferrari on LBC radio it is "highly likely" the balloons are carrying "some spy equipment".
"But it would be very useful, wouldn't it, to find out what's in it before we get our knickers too much in the twist on that," he said.
A series of objects have been shot down in western airspace by the US military in the last 10 days, including one now confirmed as a Chinese spy balloon.
Sir Michael added that it was a "very good question" why China would bother with surveillance balloons when it already has 260 spy satellites.
"That's been sort of exercising my mind. What they are getting from a balloon that they can't get from other sources is not clear to me at all," he said.
"And probably we have enough information available from satellites which they are able to get on to and, frankly, using Google and all the rest of it, would give them an awful lot of information.
"I think, possibly, there's opportunity to listen in to certain things that they might not be able to do so easily."
The retired air chief marshal also said the balloons would be shot down if they entered UK airspace, being left to "drift out towards sea" before they were downed.
"But I go back to what I said to start with, it would be very useful to find out what's actually in them before we get too excited."
His comments come as Nato defence ministers are set to meet to discuss the balloons, co-ordinate weapons supplies and continued support for Ukraine.