By Jonathan Kent
BBC correspondent in Kuala Lumpur
Chinese people worldwide have celebrated the new year
Police and civil aviation authorities in Malaysia have launched an investigation after flying lanterns released to mark Chinese New Year disrupted air traffic.
Twelve aircraft had to be diverted from the international airport on the island of Penang because of fears that the lanterns might have caused planes to crash.
The sky lanterns resemble small hot air balloons.
They are traditionally released to mark the eighth day of Chinese New Year, which this year fell on Saturday.
Thousands of the lanterns were launched after dark over the island of Penang on peninsular Malaysia's west coast.
Most of the population there are ethnic Chinese.
Penang's chief minister said the light from the lanterns had confused pilots.
There was also concern that the kerosene-powered balloons could have caused explosions if sucked into aircraft jet engines.
A number of the lanterns landed on the airport's runway, others on the roofs of nearby houses.
Police are now seeking advice on whether they have powers to ban them.
The lanterns are named after their inventor, Kung Ming, the prime minister of one of China's ancient warring kingdoms.
Made from oiled paper and bamboo, they have been known to reach heights of around 500 metres (1,600 feet).
Their original purpose was to transmit military secrets during wartime.
Later, they were used by villages beset by bandits to signal that danger had passed. They became known as 'peace lanterns'.
These days, they are set free during the lunar New Year celebrations, accompanied by prayers for prosperity.