Nearly 30 per cent of airlines worldwide are likely to defer aircraft deliveries as financing conditions deteriorate, a survey by Swiss banking giant UBS said.

Only half of the airlines polled have secured financing for aircraft deliveries this year and in early 2010, according to the survey obtained from industry sources at the weekend.

The survey covered small and large airlines worldwide, including nearly a third of operators with more than 100 aircraft on their fleet.

"Consistent with our prior survey (released in January), nearly one-third of respondents are likely to defer the delivery of aircraft currently on order," UBS said.

"Nearly all of our respondents are due to take new aircraft deliveries over the next 12-18 months with only half indicating that they have secured financing," it added.

"Overall, financing looks to have deteriorated from our prior survey with 60 per cent now indicating that they don't believe financing is currently available."

This is worse than the 55 per cent who said in the previous survey they did not believe financing was available.

UBS said 40 per cent of the airlines surveyed came from Europe, 25 from North America and 15 per cent from Asia.

Shukor Yusof, an aviation analyst with Standard and Poor's, was not surprised by the survey's findings.

"I see it worsening. There's still some way to go before the situation stabilises," he remarked.