UPDATE 1-Intl air traffic rises in Feb on leap year -IATA

(Adds detail) GENEVA, March 31 (Reuters) - International air traffic rose in February compared with the same month last year, but the extra day in the 2008 leap year hid underlying weakness, data issued on Monday showed.

Unadjusted international air cargo shipments were 5.9 percent higher in February than a year earlier, while passenger traffic rose 9.2 percent, the International Air Transport Association (IATA) said in a statement.

But the extra day this year -- Feb. 29 -- hid a continuing slowdown in demand, it said.

"When we adjust for the impact of the leap year, passenger demand increased 4 to 5 percent while freight was even more sluggish in the 2 to 3 percent range," said IATA Director General Giovanni Bisignani.

"Demand is still growing. But clearly we are in a different league from the 7.4 percent and 4.3 percent growth that we saw in 2007 for passenger and freight respectively."

The average load factor for passenger traffic, which measures the amount of seat capacity used, was 73.3 percent in February, a fall of 0.6 percentage points from a year earlier and the biggest drop in the measure for four years, IATA said.

IATA represents 240 airlines operating 94 percent of all international traffic. Domestic flights are excluded from its data. (Reporting by Jonathan Lynn; Editing by David Holmes)