HONG KONG (REUTERS) - Authorities in Macau, the world's biggest gambling hub, said withdrawals using China's state-backed UnionPay card would be suspended at automated teller machines without the latest "know your customer" technology from Tuesday (July 4).

The announcement from Macau's monetary authority is the latest in a series of measures being rapidly implemented in the special administrative region of Macau as the Chinese territory ramps up scrutiny on capital outflows from the mainland.

Earlier in May, authorities unveiled security measures including facial recognition at ATM machines which require users of China's state-backed UnionPay to provide identification.

Since May, authorities said they have installed 834 ATMs with "now your customer" functions. The monetary authority said the new move was to "promote the integrity of the financial system of Macau and enhance the protection of the legal rights of mainland card holders".

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The monetary authority said it has been working with banks to speed up the implementation to cover all ATMs in the former Portuguese colony, including those inside the casinos, by the end of this year.

In June, Macau additionally implemented new anti-money laundering legislation, beefing up the previous framework from 2006 with a much wider scope and stricter compliance measures.

The flurry of steps coincided with a visit in May by Zhang Dejiang, the head of China's Parliament and its third-most powerful leader, during which he stated Macau faced challenges.

A 2014 Reuters investigation found that many mainland Chinese use state-backed UnionPay cards to circumvent cash withdrawal limits of 20,000 yuan (S$4,067) a day, and either use that money to gamble or transfer it abroad.

Customers open multiple bank accounts, and then withdraw cash from each, or use pawn shops in Macau to make fake purchases, the investigation found.