* Air in Singapore, parts of Malaysia "hazardous"
* Singapore tells Indonesia it wants action
* Indonesia says investors from Singapore partly to blame
By Kevin Lim
SINGAPORE, June 20 (Reuters) - Singapore's air quality deteriorated to "hazardous" levels on Thursday as smoke from forest fires in Indonesia obscured skies over the wealthy city-state and parts of Malaysia and disrupted some businesses and travel.
In Singapore, air traffic controllers gave more time for aircraft between taking off and landing at Changi Airport, a major aviation hub, because of poor visibility.
Work at several Singapore construction sites slowed with few workers seen outdoors and fast-food operator McDonald's suspended its delivery service across the city-state.
In Malaysia, the air quality in parts of the country also sank to "hazardous" levels, while an Indonesian airport that serves as a base for some Chevron Corp's Indonesian oilfields was shut because of the smoke.
Singapore called on Indonesia to do something.
"No country or corporation has the right to pollute the air at the expense of Singaporeans' health and well-being," Singapore's Environment and Water Resources Minister Vivian Balakrishnan said on his Facebook page.
Balakrishnan said Singapore had sent officials to an emergency haze meeting in the Indonesian capital, Jakarta.
"We will insist on definitive action," he said.
The illegal burning of forest on Indonesia's Sumatra island, to the west of Singapore and Malaysia, to clear land for palm oil plantations is a chronic problem, particularly during the June to September dry season.
Singapore, which prides itself on its clean environment and usually enjoys clear skies, saw its air quality deteriorate to unhealthy levels on Monday.
At 1 p.m. (0500 GMT), the city-state's pollution standards index (PSI) soared to a new high of 371, indicating air quality had deteriorated to "hazardous" levels, and exceeding the previous record set on Wednesday night.
A PSI reading above 300 indicates "hazardous" air, while a reading between 201 and 300 means "very unhealthy".
The top PSI readings in Singapore over the past two days have exceeded the peak of 226 reached in 1997 when smog from Indonesian fires disrupted shipping and air travel across Southeast Asia.
Indonesian officials have tried to deflect blame by suggesting companies based in Singapore may be partly to blame for the fires. Singapore has said it wants Indonesia to provide maps of land concessions so it can act against firms that allow slash-and-burn land clearing.
"What we know is that there are several foreign investors from Singapore involved," said Hadi Daryanto, a senior official at Indonesia's Forestry Ministry.
"But we can't just blame them for this since we still need to investigate this."
Singapore-based palm oil companies with land concessions in Indonesia include Wilmar International Ltd, Golden Agri-Resources Ltd and First Resources Ltd.
All three said on Wednesday they had "zero burning" policies and used only mechanical means to clear land.
Cargill, whose Asia-Pacific regional hub is in Singapore, said there were no fires on its plantations in South Sumatra and West Kalimantan.
Researcher Jackson Ewing said that while companies may ban burning at their sites, such rules were hard for the companies and the government to enforce.
"The lack of actual control on the ground is a real issue," Ewing, a fellow at the Centre for Non-Traditional Security Studies at Singapore's Nanyang Technological University, told Reuters.