At least 2 000 police officers stationed in Boko Haram-hit northeast Nigeria on Monday demanded months of back pay in a angry protest marked by teargas and gunshots fired into the air.Members of the mobile police (MOPOL) units, who perform escort duties as well as man checkpoints and patrol with the military, demanded up to six months' arrears and better accommodation.They blocked the main road outside the police headquarters in the Borno state capital, Maiduguri, chanting slogans including "Pay us our allowances or there will be no peace."An AFP reporter at the scene said the protesters let off teargas and fired volleys of gunshots into the air.Other officers were sent out to prevent reporters covering the protest but the demonstrators stepped in to stop them, leading to scuffles, he added.One protester told AFP the last time he was paid he received only 23 000 naira ($64) - just 5 000 naira more than the national minimum wage.A "large part" had been deducted with no explanation given, he added. Officers were unable to give money to their families for food and school fees, he said."How do they expect us to maintain security when we are hungry and frustrated, when we haven't seen our families for months and can't discharge our basic responsibilities as husbands and fathers?" he asked."Our patience has been exhausted. All we are saying is they should give us our money."Another said they had not been paid for six months while provision of food had been stopped and officers have been forced to sleep in the open as there was no accommodation.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. There was no immediate comment from the police authorities.Non-payment of salaries is not unusual in Nigeria, particularly in recent years, as the country slid towards recession after the collapse of global oil prices from mid-2014.In 2015, public sector workers in 30 out of Nigeria's 36 states were owed wages. In recent months, university staff, oil and gas workers and hospital doctors have gone on strike over salary arrears dating back as far as 2009.Under former president Goodluck Jonathan, soldiers complained of non-payment of salaries, as well as lack of adequate weapons and even ammunition.In one case, troops refused an order to deploy for an offensive against the jihadists. President Muhammadu Buhari was elected in 2015 on a pledge to defeat the Islamists and tackle endemic corruption.