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Lagos, Nigeria (CNN) -- Two Nigerian trade unions accused the country's president of using "armed thugs" to attack protesters, and urged demonstrators to continue their nationwide strike against high fuel prices on Wednesday and beyond.
"In a Mubarak-style response to the peoples' protests, the Jonathan administration brought into Abuja, thugs armed with various weapons including guns," the Nigeria Labour Congress and the Trade Union Congress of Nigeria said in a joint statement late Tuesday night.
The unions were comparing President Goodluck Jonathan to former Egyptian President Hosni Mubarak, who is accused of ordering security forces to fire on protesters in Egypt last year.
"Labour warns the Presidency that it will be held responsible for whatever atrocities these thugs commit," the statement said. "We call on Nigerians to continue the strikes, rallies and protests ... Wednesday ... and subsequent days until the Jonathan government listens to the voice of the Nigerian People."
Government spokesman Reuben Abati denied the accusations and said negotiations between the labor unions and the government are under way.
"If these claims are properly investigated, you will find out that failed and bitter politicians have not only hijacked this protest, but have diverted it from a protest against deregulation policy," he said Reuben Abati.
Wednesday will mark day three of the strike, which was spurred by a government decision to remove fuel subsidies -- a move that resulted in more than doubled fuel prices in the largely impoverished country.
So far, clashes have left at least 16 people dead and 205 injured, according to a tally collected by the Nigerian Red Cross Tuesday.
The strike, continued religious violence in the north and a long-simmering separatist movement are all issues that have created growing problems for Jonathan and fueled tensions on the street.
The southern state of Edo was a focus for much of the violence, according to the Red Cross, with five people killed and 83 injured.
"Revolution has come to Nigeria and the youth will spearhead it. Until our demands are met, we are ready to protest every day and make sacrifice," said Eromo Egbejule, a Nigerian freelance journalist.
Other violence erupted in northern Nigeria Tuesday and Wednesday, although it was unclear whether the incidents were related to the strike.
In Yobe state, four people died Wednesday after two gunmen on a motorcycle stopped next to a car filling up at a gas station and opened fire on the occupants in the town of Potiskum, about 600 kilometers northeast of Abuja, said Lawan Tanko, Yobe state police commissioner.
"We don't know if it's Boko Haram or other criminal elements," he said. "We are still investigating." The victims' ethnic groups had not been confirmed, he said.
Boko Haram, a shadowy militant Islamic group that is said to favor strict Sharia law, is frequently blamed for sectarian violence.
Also in Yobe state, eight people drinking in an open-area bar, including a police officer, were shot to death Tuesday by several unidentified gunmen in Potiskum, Tanko said. The gunmen opened fire without announcing their presence, he said.
No one has claimed responsibility, and police are not sure who was behind the attack, he said.
In a recent address, Jonathan tried to explain the need for ending the subsidies, telling Nigerians that the government would invest the money in the country's crumbling infrastructure.
"My fellow Nigerians, the truth is that we're faced with two basic choices with regards to the management of the petroleum sector," Jonathan said. "Survive economically or continue with a subsidy regime that will continue to undermine our economy."
Some analysts say the changes could help Nigeria in the future.
"If they're prepared to try this petroleum subsidy removal then perhaps they can push through electricity reform too. If they do that, Nigeria's growth can be instead of 7%-8% a year, 10% or 11%," said Charlie Robertson, a chief economist at the global investment firm Renaissance Capital.
But assurances from the president did not allay fears from many Nigerians who do not trust the government to use the money to improve the country's infrastructure.
Many Nigerians view the subsidy as the only benefit of living in an oil-producing country that has little infrastructure, poor roads, high unemployment and intermittent electric power.
"Though we know that in the long run, removal of (the) subsidy will help the economy, for now it is a high-profile lifestyle that is unbearable for most Nigerians, and soon the poorer ones will die out," said protester Diane Awunah.
CNN's John Defterios, Jack Maddox and Michael Saba, and journalist Vladimir Duthiers contributed to this report.