Taiwan Semiconductor Manufacturing has reported better-than-expected first-quarter net profits, mostly thanks to a stronger Taiwan dollar.

Chief Executive Rick Tsai said TSMC's net profit in the three months ended March 31 rose 49 percent to $925.6 million. Revenue in the first quarter rose 34.8 percent over last year.

Analysts had expected TSMC to outperform rivals United Microelectronics and Singapore's Chartered Semiconductor because of its diversified client base. They said TSMC's competitors likely suffered from seasonal weakness in demand and pricing pressures.

Chartered Semiconductor reported a 62 percent drop in first-quarter net profit to $2.39 million from $6.33 million on higher research and development costs and payroll-related expenses.