A Singapore Airlines (SIA) cargo plane is undergoing repairs in Brussels after holes were spotted on the bottom of the aircraft.

The affected plane was a Boeing 747-400 freighter operating the SQ7951 service from Dallas to Brussels on Feb 26, SIA said yesterday.

The flight crew had conducted the necessary aircraft visual checks according to procedure.

The flight then took off and landed in Brussels without incident, the carrier added.

But the plane was "found to have had some damage on its body during a post-flight inspection".

SIA said: "Investigations are under way to determine the cause of the damage. The aircraft is undergoing repairs at Brussels and will return to Singapore after the repairs have been completed."

Aviation news website The Aviation Herald had posted photos showing what it said were multiple punctures on the bottom of the plane. In one photo, a rock is seen stuck in one of the holes.

The website suggested that the damage was caused by stones thrown upwards by aircraft wheels while the plane was landing on the runway.

It said initial information had suggested the stones had fallen off a truck being used for renovation works at the Brussels Airport.

SIA now operates a fleet of seven Boeing 747-400 cargo planes. The planes had been used to ferry the initial shipments of both the Pfizer-BioNTech and Moderna Covid-19 vaccines from Brussels to Singapore in recent months.

The global airfreight crunch has seen SIA's cargo load increase with strong demand for pharmaceutical and e-commerce shipments.

SIA has also stepped up the frequency of passenger aircraft operating cargo-only flights, and resumed more passenger services.