Nigerian President Bola Tinubu declared a state of emergency on Tuesday in oil-producing Rivers State and suspended the state governor, his deputy and all lawmakers.

Tinubu, in a television broadcast, said he had received security reports in the last two days of "disturbing incidents of vandalization of pipelines by some militants without the governor taking any action to curtail them."

"With all these and many more, no good and responsible president will standby and allow the grave situation to continue without taking remedial steps prescribed by the constitution to address the situation in the state," added Tinubu.

Police said earlier they were investigating the cause of a blast in Rivers state that resulted in a fire on Nigeria's Trans Niger Pipeline, a major oil artery transporting crude from onshore oilfields to the Bonny export terminal.

Rivers, in the Niger Delta, is a major source of crude oil and militants have in the past blown up pipelines, hampering production and exports.

The state has been embroiled in a political crisis pitting factions of the opposition People's Democratic Party (PDP) against each other. The state lawmakers had also threatened to impeach the governor and his deputy.

Tinubu's state of emergency enables the federal government to make regulations to run the state and also allow authorities to easily deploy security forces to bring order if needed.

Tinubu nominated a retired vice admiral as caretaker to run the affairs of Rivers State for an initial six months.

The president said he had sent a copy of his proclamation to the National Assembly, which can endorse or reject his decision.

"For the avoidance of doubt, this declaration does not affect the judicial arm of Rivers State, which shall continue to function in accordance with their constitutional mandate," said Tinubu.