Nigerian airlines are canceling flights as a month-long fuel shortage is aggravated by a strike disrupting fuel deliveries in Africa’s biggest oil producer.

Vehicles also are grounded. Normally bustling roads in Lagos, a metropolis of 20 million, were half-empty and gas stations closed Saturday.

Police are arresting black marketers selling fuel at roadsides at inflated prices.

Chaos reigned at bus stations and Lagos’ Murtala Muhammad International Airport as flights were canceled.

The fuel shortage started with oil suppliers demanding that the government pay alleged arrears of nearly $1 billion.

It comes as Nigeria prepares to inaugurate a new president, Muhammadu Buhari, on Friday.

•Adapted from an AP report. Photo shows Murtala Muhammad International Airport.