The Chinese casino hub, which has its own legal system largely based on Portuguese law, enacted a national security law in 2009 and widened its powers in 2023.

Macau's judicial police said a 68-year-old local man surnamed Au was arrested and handed over to public prosecutors on suspicion of "establishing connections... outside Macau to commit acts endangering national security".

The man allegedly provided "a large amount of false and seditious information" for public exhibitions and stirred up hatred against the Macau government.

He is accused of disrupting the city's 2024 leadership election and causing foreign countries to take hostile action against Macau, according to the police statement.

Online news platform All About Macau reported that judicial police took away the ex-lawmaker and his wife Virginia Cheang on Wednesday.

Cheang told the outlet outside the public prosecution office that she was listed as a witness and that she did not know why her husband was detained.

AFP was unable to reach Au for comment.

Au, a primary school teacher who became one of Macau's longest-serving pro-democracy legislators, did not seek re-election after his term ended in 2021.

The former Portuguese colony reverted to Chinese rule in 1999 via a "One Country, Two Systems" framework that promised a high degree of autonomy and rights protections.

But Beijing tightened its grip on Macau, including the ousting of opposition lawmakers, after neighbouring Hong Kong saw months of huge and sometimes violent pro-democracy protests in 2019.