In the first incident, they stripped excavator parts from various machinery at a construction site along Kranji Way.

The parts, worth about $6,000, belonged to three construction firms.

One of the owners, a 50-year-old man, said he left the site at 4.30pm on Jan 8 and returned the next day at 8.30am to find the parts, which included controller boards, fuel gauges and hydraulic pumps, missing.

In the second theft, eight metal poles, to be used as barriers for trailers of heavy vehicles, were stolen.

Each steel pole, measuring one metre long and 20 cm in diameter, weighed 30 kgs.

A 50-year-old trailer driver said he had bundled the eight poles and secured them together with a chain and padlock.

He left them under the trailer of his heavy vehicle which was parked along Bukit Batok Road.

He left the vehicle at about 5pm on Jan 8 and when he returned the next morning at 9am, the bundle of poles, chain and padlock were missing.

The steel poles were worth about $800.