Barely 5 per cent of the rated project and infrastructure companies in Asia Pacific have high exposure to coronavirus disruptions, Moody's Investor Service said on Wednesday.

Pressure has eased for Chinese toll roads, while a small number of utilities face moderate exposure, it said.

A high proportion (67 per cent) of rated project and infrastructure companies in Asia Pacific continue to have low exposure to the coronavirus-related disruptions, supported by their essential nature and predictable cashflows, Moody's Investors Service said in a statement.

"The number of companies with high exposure has reduced in recent months, particulary the Chinese toll road sector following the end of the toll-free period and with recovering traffic volumes," said Arnon Musiker, senior vice president and manager at Moody's.

Airports now make up most of the high exposure category, he said.

Whereas Moody's in April estimated 9 per cent of project and infrastructure companies had high exposure to coronavirus disruptions, this number has now declined to 5 per cent.

"On the other hand, a small number of power utilities now have moderate exposure to coronavirus disruption, given rising pressure from falling power prices and lower demand, which is only partly offset by lower fuel costs," the statement said.

Following the reclassification of these toll roads and utilities, the number of companies with moderate exposure has increased to 28 per cent from 23 per cent in April.

"Moreover, a limited number of projects with exposure to commodity risk - particularly energy-related - also face rising challenges following the recent material fall in oil, gas and coal prices," Musiker said.

Still, the majority - 67 per cent - of companies face low exposure, and include regulated utilities, projects and public-private partnerships, the statement said adding, this risk exposure for regulated networks remains low notwithstanding temporary tariff relief measures instituted by certain companies, given their temporary nature and immaterial effect on metrics.