SEOUL: The South Korean won weakened for a third straight session on Monday, ending near five-week lows on increased dollar demand in the wake of tensions with China over Seoul's decision to deploy a US missile defence system.

The won was quoted at 1,158.0 to the dollar at the conclusion of onshore trade, its lowest since Feb. 1. It was down 0.2 percent compared with Friday's close of 1,156.1.

South Korean shares reversed earlier losses supported by strong foreign stock purchases.

The Korea Composite Stock Price Index (KOSPI) closed up 0.1 percent at 2,081.36 points.

Offshore investors bought a net 232.1 billion won ($200.57 million) worth of KOSPI shares for the day.