LONDON (Reuters) — British Airways reported strong figures for its premium class seats in June yesterday, lifting its shares which shrugged off uncertainty caused by an attempted terror attack last week.BA said a 1.4 percent improvement in premium volumes — mainly first class and business class — was more than offset by a 1.9 percent decline in economy class.

But its shares, which were already up 2 percent, jumped further after the statement, and were up 5.2 percent at 440 pence by 15.09 GMT.

"There's a bit of hope coming back in," said one London analyst. "The premium traffic increase beat what goes for consensus."

The airline cancelled 108 flights on Tuesday, out of about 450 world-wide, after a suspect bag at London's Heathrow airport forced an evacuation. Security measures have been ramped up after two men rammed a burning Jeep into Glasgow airport on Saturday.

Investor relations chief George Stinnes said it was too early to assess the impact on forward bookings of the latest security clampdown at UK airports.

"A burning Jeep Cherokee at Glasgow — those kind of images are not very good, but then the police are demonstrating that they're very much on top of things," he said.

But Stinnes said the evacuation at Heathrow would cause problems for days.

"The terminal being closed for five hours is an enormous disruption of processes," he added. "There's an impact on baggage. It's very difficult to recover because Heathrow is so small."

The airline said the overall 1.4 percent decline in passenger volumes caused its load factor — a closely watched measure of how well it filled its planes — to slip by 1.4 percentage points to 80.5 percent.

Stinnes said the airline had expected premium volumes to remain broadly unchanged from last year's strong numbers, after security measures on bags made transfer traffic more difficult for passengers.

"The banking community is doing very well, and the corporate community is flying a lot too," he added. "The underlying demand for premium travel is good."

BA's overall load factor fell 3.7 points to 75.2 percent on routes in Britain and Europe, and by 2.5 points to 84 percent on routes to the Americas.