KUALA LUMPUR (Reuters) - Malaysian anti-corruption authorities said they had arrested on Wednesday a senior national opposition leader who has been under investigation for abusing his position as chief minister of Penang.

The Malaysian Anti Corruption Commission (MACC), in a statement, said Lim Guan Eng was arrested at his offices in Penang, an opposition-held state.

Lim, who is also secretary-general of the federal opposition Democratic Action Party, will be detained until Thursday morning when he is expected to be formally charged, a MACC source said.

The exact charges he faces were not spelt out.

The MACC said in March this year that it started investigating Lim after a report which accused him of abusing his position by securing a two-storey bungalow on the island state at below market price in July last year.

(Reporting by Joseph Sipalan; Editing by Richard Balmforth)