Nigeria's President Bola Tinubu has declared three days of national mourning after a military aircraft crashed in southern Ondo State, killing 32 people.

Authorities say the plane was on a routine mission from Benin City to Lagos when it came down near a naval base on Monday morning.

A resident told the BBC that the plane had crashed near a swamp and that clothes and shoes had been found at the site. Smoke could be seen rising from the area.

Tinubu offered his deepest condolences for the 25 passengers and seven crew members on board and has ordered a full investigation.

The president also ordered national flags to be flown at half-mast across the country as a mark of respect for those who died.

"This is a painful moment for our Armed Forces and for the entire nation," Tinubu said.

"Our Air Force personnel put their lives on the line every day to secure Nigeria. Their sacrifice will never be forgotten," he added.

Aviation Minister Festus Keyamo earlier said he had been informed: "of the disappearance of a military aircraft with tail number NGR 931, en route from Benin to Lagos at 0913 hours earlier today".

He said "efforts to raise the aircraft on radio proved abortive" before subsequent confirmation that it had crashed near a naval base in Igbokoda, Ondo State.

He said search and rescue efforts were ongoing.

The crashed plane, described as an ATR-42 aircraft, carries between 30 and 50 passengers, according to its manufacturer.

Tinubu has ordered the Air Force to immediately begin a thorough investigation into the cause of the crash to help prevent similar incidents in the future.

The identities of those who died have not yet been released. Authorities say the names of the officers will be published after their families have been informed.

The Nigerian Air Force plays a key role in the country's military operations, including efforts to tackle armed groups and insecurity in several parts of the country.

The accident is one ​of the deadliest air disasters ​in ⁠Nigeria in recent years.

In May 2021, Nigeria's army chief, Lt-Gen Ibrahim Attahiru, was killed in a plane crash alongside 10 other officers in the northwestern state of Kaduna amid bad weather.

In February of the same year, seven people died after a military plane crashed short of a runway in the capital, Abuja.