Philippine President Ferdinand Marcos signed a law on Monday requiring mobile users to provide personal details when buying a SIM card, a regulation aimed at combating text messaging fraud.

The bill was passed by both houses of Congress in September after a controversial provision requiring social media users to register their real names and phones numbers was dropped.

Former president Rodrigo Duterte had rejected the original legislation.

Filipinos rank among the world's heaviest users of social media, and the country has become a key battleground for misleading or fake news.

"We will finally achieve what has long been overdue - an effective means of regulating the issuance of SIM cards to curb the spread of spam text messages and scams," Marcos said, who was signing his first law since taking power in June.

Many mobile phone users in the Philippines use pre-paid SIM cards that they buy over the counter without giving their names and addresses to 

providers.

Under the new law, they will have to show photo identification and complete a registration form with their personal details, which will be kept by the mobile service provider.

It will be applied to tens of millions of existing users, who risk being disconnected if they do not register within a certain period.

The government hopes the law will enable law enforcement to combat spam and scam text messages, many of which offer fake jobs or promises of prize ­money. 

But Renato Reyes, secretary-general of leftist alliance Bayan, said the new legislation was a "problematic response" and could undermine privacy rights.

While most countries have mandatory SIM card registration, dozens do not require it, including the US and Britain, according to UK-based Privacy International.