Delta Air Lines , the world's largest carrier, said on Tuesday it would cut its international capacity by an additional 10 percent starting in September as the global economic downturn batters the industry.

Delta said its cuts would target its Atlantic and Pacific networks, which have seen the most revenue weakness. The cuts are in addition to a systemwide capacity decrease announced late last year.

While flying held up somewhat in the second half of last year, it was just a matter of time until the rest of the world started to slow down, said Basili Alukos, a Morningstar analyst.

From the international perspective, most of the airlines are just late to the game, he added.

Delta said its transatlantic capacity this winter would be down 11 percent to 13 percent compared to the winter of 2008, while its transpacific capacity would be down 12 percent to 14 percent.

The airline industry is grappling with weaker travel demand as economies sag around the world. Carriers slashed seat capacity in the second half of 2008 to compensate for volatile fuel prices and falling demand, and analysts have been expecting further cuts.

Delta, which merged last year with Northwest Airlines, said in December its domestic capacity would fall 8 percent to 10 percent in 2009, and international capacity would fall 3 percent to 5 percent. Systemwide, that meant a reduction of 6 to 8 percent.

The new round of downsizing means Delta must reassess our staffing needs, the company said in a memo to workers. The carrier has eliminated 2,100 jobs through voluntary exit programs and hopes to achieve its next target also through voluntary separation. Delta has more than 70,000 employees.

Delta also said it expects its first-quarter operating margin to be down 6-7 percent and breakeven pretax earnings at current fuel prices. Excluding one-time items, the carrier said it sees its first-quarter operating margin down 5 percent to 6 percent. Delta said it expects to end the first quarter with a liquidity position of $4.4 billion.

Delta's shares were up 13 cents at $4.30 in morning New York Stock Exchange trading after earlier climbing as much as 8 percent.

(Reporting by Karen Jacobs in Atlanta and Kyle Peterson in Chicago, editing by Dave Zimmerman)