Protesters in Zimbabwe barricaded the main roads into major cities on Monday to protest a fuel price rise announced by President Emmerson Mnangagwa.

In the southern city of Bulawayo, commuter bus drivers and activists blocked thoroughfares with burning tyres, tree branches, and blocks of stone. Riot police tried to quell demonstrations in the western suburbs of Emakhandeni and Luveve, firing warning shots and tear gas, but the protesters remained defiant. 

Demonstrator Glen Ncube, 25, expressed anger at the president's announcement on Saturday of a 150 percent fuel price increase and the police actions. 

"What kind of a man does this? Can Mnangagwa even be called a president? He's making life hard for us and these police are trying to stop us as if they don't know our pain," said Ncube.

The government has vowed it "will not hesitate to take action" against protesters who threaten to destabilise the country and the military was deployed to assist police.

Zimbabwe is going through its worst economic crisis in a decade.

The government announced an increase from $1.34 for a litre of petrol to $3.31 with diesel surging to $3.11 per litre, igniting widespread discontent. Workers' trade unions have called for a three-day nationwide shutdown in protest. The action comes shortly after junior doctors ended a 40-day strike demanding salaries in US dollars and better working conditions. 

Since the crash of the hyperinflated Zimbabwe dollar in 2008, the country uses several currencies including the US dollar and its unpopular local surrogate called the "bond note". Because of a severe shortage of foreign exchange, most daily transactions are done in bond notes with the US dollar and South African rand trading on the black market at inflated rates. 

Morrisson Nxulmalo, an unemployed 33-year-old Zimbabwean, told Al Jazeera he was prepared to protest until the government reversed the price increase.

"The fuel prices must come down, we are not going anywhere until they bring it down. This government is trying to play with us. They can bring their tear gas and police but we're here to fight for this country; I'm not going anywhere," he said.

A shopping complex in neighbouring Entumbane was looted with people carrying out crates of food and drinks and bottles of cooking oil while police battled to stop them from entering the shops.

In Bulawayo's city centre, people marched to the court and disrupted proceedings. Crowds swelled as ordinary citizens joined with protesting activists to add their voices to the anti-fuel price demonstrations.

The commuter fares have doubled due to the price rise since Saturday's announcement while some businesses shut their doors to protect stocks from potential looters. 

The government of Zimbabwe issued a statement condemning the riots as Western-sponsored acts.

"This brazenly unconstitutional plan which has sought financial support from some regime change organisations based in America and Germany, among other countries, represents a serious threat to our consolidating democracy, to the rule of law in our country, and to the authority of government and the state," the statement said. 

In Epworth, a low income area outside the capital Harare, four people were reportedly shot by security officers while eight people were arrested. Media reports from Harare also said police conducted house-to-house searches looking for protesters.

The headquarters of the opposition Movement for Democratic Change Alliance was under police surveillance. Party leader Nelson Chamisa - who narrowly lost to Mnangagwa in July's disputed election - has called on the president for dialogue to find ways to resolve the country's crippling economic crisis. 

Following a de facto coup in November 2017 long-time ruler Robert Mugabe stepped down, and after a disputed election in July that saw Mnangagwa elected into office, the leader has promised an economic turnaround for the impoverished African nation.

However, since the government's introduction of a two percent transaction tax in October, Zimbabwe's money woes have worsened and inflation has soared to double-digit figures since then. 

Mnangagwa is currently in Moscow, Russia, as part of a tour of Eastern Europe where he hopes to solicit investors and strike deals in a bid to help Zimbabwe's ailing economy.