A Singapore graft probe involving Transport Minister S. Iswaran was expanded to include property tycoon Ong Beng Seng, who was given a notice of arrest.

Ong was asked to provide information on his interactions with the minister, Singapore-based Hotel Properties Ltd. said in a stock exchange filing Friday. No charges have been filed against Ong. He will surrender his passport after returning to the country as he will be traveling from today.

Prime Minister Lee Hsien Loong earlier this week said he instructed Iswaran to go on leave as the Corrupt Practices Investigation Bureau started an investigation that would involve interviewing the minister and others. It’s the first graft probe by the CPIB, which reports directly to the PM, involving a cabinet minister in almost four decades.

Hotel Properties has a portfolio of nearly 40 hotels and resorts across 15 countries including the Four Seasons in Singapore and the Maldives, according to its website.

The CPIB did not respond to an earlier query sent by Bloomberg News outside office hours.

Read more: Singapore Minister Faces Most Serious Graft Probe Since 1986

--With assistance from Chanyaporn Chanjaroen.

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