LAGOS, Nigeria—Nigerian airlines grounded flights on Saturday and radio stations were silenced, as a monthslong fuel shortage aggravated by striking oil-tanker drivers worsened in Africa's biggest oil producer.

Vehicles also were grounded. Normally bustling roads in Lagos, a metropolis of 20 million, were half-empty and gas stations closed on Saturday. One station owner said he had fuel, but strikers were threatening to set fire to any stations selling it. He insisted on anonymity for fear of reprisals.

Police were arresting black marketers selling fuel at roadsides at four times the regulated 87 naira (40 cents) a liter.

Meanwhile, radio stations went dead on Saturday night, including Classic FM, The Beat and City FM, hit by frequent power outages and out of diesel fuel for generators.

Confusion reigned at bus stations where vehicles stood idle and at Lagos' Murtala Muhammad International Airport, as one flight after another was canceled. "All flights suspended or canceled. No fuel. Been sitting here since 6 a.m.," one customer complained on Twitter.

Aero Contractors, one of Nigeria's largest private airlines, canceled 80% of its flights, said spokesman Simon Tunde.

Passengers said Air France and Kenya Airways flights were diverted to Dakar, Senegal, and Cotonou, Benin, to refuel on their way to Paris and Nairobi because no fuel was available in Lagos this week.

Nigeria produces more than 2 million barrels of petroleum a day but imports refined fuel products because it doesn't have enough functioning refineries. It regularly suffers fuel shortages but nothing as severe as the current countrywide crisis.

The crisis started weeks before the March 29 elections, with oil suppliers hit by tightened credit lines amid halved international oil prices, a slump in the naira currency and unpaid government debts the suppliers claim amount to nearly $1 billion.

Unpaid oil tanker drivers went on strike earlier this month and other industry workers joined them this week.

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