* Motorist secretly films policeman extorting $160
* Dismissal a rarity in corruption-plagued Nigeria
* Racketeering goes up police chain of command, analysts say
* Spokesman dismisses policeman as lone wolf
By Tim Cocks
LAGOS, Aug 8 (Reuters) - It was a crime so familiar to inhabitants of Nigeria's corruption-ridden main metropolis that few would have batted an eyelid had the victim not managed to record the whole incident on a secret camera.
The outcome was much rarer - a policeman sacked for trying to extort money from a motorist over a supposed traffic offence.
It was a scene that happens every day. A policeman stops a car on a busy Lagos street and accuses the driver of flouting some traffic rule - one that may be real or imaginary in a vast, chaotic city of 21 million people where motorists often seem oblivious to any rules.
The policeman then opens the door to the passenger seat, enters and demands a large amount of money from the motorist - in this case 25,000 Nigerian naira ($160).
Nigeria's central police command confirmed overnight that Sergeant Chris Omeleze had been dismissed after being caught on camera trying to extort the bribe from a motorist who was leaving Lagos international airport.
"I want to gladly report that in less than 24 hours after we got wind of that story, the police officer was identified, arrested ... (and) dismissed from the police force," police spokesman Frank Mba said on Channels Television on Thursday. Omeleze had been a policeman for 21 years, said Mba.
The video has received 117,500 hits on YouTube, been retweeted and replayed on all Nigeria's main TV channels.
Omeleze originally asks the driver for 25,000 naira but the man protests that 2,000 naira is all he has.
The policeman says this is not enough, adding: "I am not working alone. Look, if you enter this compound (the police station), you will pay bigger money."
He then appears to notice the man has some dollars, but the driver says that he needs them for excess luggage.
After much argument, the policeman appears to make a phone call to a colleague and tells him the driver refuses to pay up. He then advises the driver that he had been instructed to book him for the traffic offence.
Analysts say corrupt police officers in Africa's most populous country do not work alone but are part of a mafia-like racketeering network going far up the chain of command.
It often worsens during election cycles when politicians, who wield influence over police, need more money for patronage.
Mba denied that the policeman had an accomplice in the precinct station, saying he made a pretend call in order to "blackmail" the motorist he had pulled over.
"As a matter of fact he made no calls. He wanted to fool the citizen into believing there were some superior forces involved."
It was not known whether the sacked policeman would be prosecuted, as Mba could not be reached for further comment.
($1 = 160 naira) (Editing by Joe Brock and Mark Heinrich)