A pilot and a co-pilot have tested positive for alcohol after the plane they were operating veered off the runway when landing in Nigeria.

The Nigerian Safety Investigation Bureau (NSIB) screened the pair after the accident in July at the Port Harcourt International Airport. In addition, a crew member tested positive for cannabis.

All 103 people on board the Boeing 737 at the time of the incident were unharmed.

Air Peace, the company that operated the flight, said the 64-year-old pilot has been sacked for failing to adhere to safety regulations, while the co-pilot has since returned to his role.

In a statement, Air Peace said the co-pilot was acquitted by the national regulator, the Nigeria Civil Aviation Authority (NCAA), following preliminary investigations and a clean bill of health.

Tests carried out by the NSIB found the pilot and co-pilot had tested positive for Ethyl Glucuronide (EtG), which indicates recent alcohol consumption.

A cabin crew member also tested positive for (THC), the psychoactive component in cannabis.

In a statement, Air Peace said it had not received any toxicology test results from the NSIB.

"We are yet to receive any official communication from the NSIB on such findings over a month after the incident and after the testing of the crew for alcohol which took place in less than an hour of the incident," Air Peace said.

The pilot had a total flying time of over 18,000 hours, while the co-pilot, aged 28, had almost 1,200 hours.

The NSIB says its investigations are still in progress. For now, it has recommended improved training and the reinforcement of internal procedures.

Although there have been no plane crashes in Nigeria for several years, there have been cases of aircraft overshooting the runway and tyres bursting during landing.

Earlier this month, aviation authorities launched a new flight data centre aimed at improving aircraft safety, but stakeholders say further protective measures and improved technology need to be deployed in the sector.