'The major task here is to clear all ant colonies with pesticide,' said Sai Kung district lands office senior executive Kwong Shiu-ming.

Residents' representatives said many people were concerned. 'The government land is just across the road and the only thing between our turf and the red fire ants is Tong Chung Street,' said Sam Ng Shuet-shan, vice-chairman of the estate's incorporated owners.

'Flat owners keep calling me as they fear the ants might invade our homes.'

Mr Ng said some parents took their children to play in the open area. 'Luckily, no one has been bitten so far,' he said.

The ant's tail can cause a vicious sting.

The government land, sandwiched between Tong Chung and Tong Yin streets, is managed by the Lands Department.

Former president of the Federation of Asian and Oceania Pest Managers Association Jackson Chan Chak-shum, who inspected the area yesterday, estimated there were more than 100 red fire ant nests.

'Judging from the size of the mounds [which are about 30cm high and 30cm long], they are still in their initial stage,' he said.

'Each nest has hundreds of thousands of ants. Compared to the ones first spotted in Hong Kong in 2005, these mounds are quite small.'

Mr Chan dismissed residents' fears, saying it was unlikely the ants would invade their homes.

'Red fire ants like staying in bare land where they are left alone. They do not like cement roads and concrete buildings either,' he said.

A report on the ants was received in February, the Food and Environmental Hygiene Department said.

'The road is in a public area and is very close to the government land,' a department spokesman said.

'A cleanup was carried out after the reports about the red fire ants were received,' he added. 'We also conduct regular inspections of the road.'

A total of 2,600 red fire ant mounds have been found across Hong Kong since 2005, when the species was first spotted in the city.