Edmund Koh, DBS's head of regional consumer banking, said there had been an increase in foreigners taking up loans, from 5.6 per cent of the total new loans book last year to 7.8 per cent for the year to date.

United Overseas Bank executive vice-president Eddie Khoo disclosed last month at the bank's second-quarter results that foreigners account for about 10 per cent of home loans. Overall, too, the bank was being cautious, given the market conditions.

'As you know, property prices are moving up quite rapidly,' said Mr Khoo. 'But what's good is that we are seeing less than 10 per cent of loans being booked (with) more than 80 per cent financing. We have a good portion of customers putting in more cash and equity in the purchase of property.'

Dr Chua said that banks were becoming more cautious in extending property loans to foreigners, especially in cases where prices were sizzling and people were buying for investment.

Anecdotally, he was aware of several cases where people could not get valuations to match their purchase prices.

For the mid-tier segment and if it is for owner occupation, banks are still more relaxed in their loan criteria, Dr Chua said.

Mortgage growth had been sluggish for several months despite the Singapore property boom.

UOB and DBS said their Singapore mortgage book grew at 15 and 14 per cent respectively in the first half of this year.

There is little similarity between US lending practices and those in Singapore, where the banks have a good buffer in their exposure to mortgages. Although the Monetary Authority of Singapore eased financing limits from 80 per cent to 90 per cent two years ago, most banks said the bulk of their loans are booked at not more than 80 per cent financing.

They also said that investment properties do not account for more than 20 per cent of total loans