Ong was asked to provide information on his interactions with the minister, Singapore-based Hotel Properties Ltd said in a stock exchange filing on Friday.

No charges have been filed against Ong, who will surrender his passport after returning to the country as he will be travelling 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 is the first corruption probe by the CPIB, which reports directly to the prime minister, 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.