(Updates throughout, adds context)

SINGAPORE Sept 12 (Reuters) - GlobalFoundries, the world's third-largest contract chipmaker, opened a $4 billion semiconductor fabrication plant in Singapore on Tuesday, as part of a major global manufacturing expansion.

The U.S chipmaker's new 23,000 square meters (248,000 square feet) facility will be able to produce 450,000 300 millimetre wafers per year at full capacity, expected by 2025 to 2026, and will create 1,000 jobs, the company's Singapore general manager Tan Yew Kong told reporters.

"If we run (the Singapore campus') capacity to the fullest, that will probably be (around) 45% of revenue for GlobalFoundries," he said, adding that the company expected weak global demand for chips to pick up by the second half of 2024.

The company's Singapore operations, which serve 200 clients worldwide, also include two other fabs that produce 720,000 300mm wafers and 692,000 200mm wafers a year respectively. The chips are used in cars and 5G technology.

GlobalFoundries announced a $6 billion global expansion in 2021 amid a chip shortage during the pandemic that has since reversed into a surplus.

One of GlobalFoundries' biggest clients is Qualcomm , which said on Monday it had signed a deal with Apple

GlobalFoundries is the world's third-largest foundry by revenue behind Taiwan's TSMC and South Korea's Samsung Electronics, according to market intelligence provider TrendForce.

Singapore's overall semiconductor output, which makes up 11% of the global market, is set to grow as more chipmakers open or expand operations in the coming months. (Reporting by Fanny Potkin; Editing by Richard Chang and Jamie Freed)