UPDATE 2-BA July traffic rises, expects summer upturn

* Says July passenger numbers up by 1.0 percent

* Premium traffic still suffering, down 11 percent

* Volumes expected to improve over summer months

* Shares up 7 percent (Adds company comment, shares)

LONDON, Aug 5 (Reuters) - British Airways BAY.L carried 1 percent more passengers in July than the same month a year ago, while its shares spiked as it said further gains were expected over the rest of the summer.

The airline, which last week reported its first ever Q1 loss and said it saw no signs of an industry recovery, said in a Wednesday statement its load factor -- a measure of how well it fills planes -- rose 3.1 percent to 84.6 percent.

"Underlying volumes and seat factors are expected to improve in the peak summer months," the carrier said, although business or premium passenger numbers continued their downward slide, falling 11 percent year-on-year.

George Stinnes, group head of investor relations, told reporters that while the summer was now looking good the airline still had no way of knowing how it would fare in September -- one of its most important months.

"People are tending to book much, much later -- September is a big month for business travel but with late bookings, its hard to see how that will come across," he said.

Airline shares around the world were on the up on Wednesday following robust July traffic figures from U.S. carriers. [ID:nL5218304]

BA shares were up 7.1 percent at 161 pence by 1429 GMT, making it a 25 percent jump over the past month. Irish low-cost carrier Ryanair (RYA.I) flew 19 percent more passengers in July than in the same month last year, on a load factor of 89 percent. [ID:nWLA0651] (Reporting by John Bowker, Editing by Ben Deighton and Rupert Winchester)