NIGERIA’S main labour unions will begin an indefinite strike on Monday to protest an increase in power and petrol prices, the leader of the body said, after a meeting with the government two weeks ago ended in a deadlock. The Nigerian Labour Congress, which represents millions of workers across most sectors of Africa's biggest economy, including parts of the oil industry, plans to embark on a general strike starting next week, leader Ayuba Wabba said. A reversal of the petrol and power price hikes would avert the strike, Wabba said in a statement. The government has not yet responded to…