CLP said on Wednesday there were "no obvious signs" of foul play in a fire that swept through a power cable bridge in Yuen Long last month that led to a blackout in the area.

In a detailed report to the government, the power firm said the cause of the fire cannot yet be determined until the full results of various laboratory tests and analyses are available.

It added that hot weather did not appear to be a contributing factor.

CLP said before the bridge burst into flames on June 21, there were no known operational or fault incidents in the power supply system in Yuen Long, Tin Shui Wai and Tuen Mun.

"The cables were operating below their design load limit, and there was no overloading issue," the company said in a statement.

CLP said it agreed with the Fire Services Department and other government departments that "at present there are no obvious signs that the fire resulted from foul play".

The firm said security systems and fire protection equipment at four other cable bridges around the city have been enhanced after the Yuen Long fire.