Venezuela is on the "brink of disaster", Foreign Secretary Boris Johnson said as he urged the country's president, Nicolas Maduro, to abandon plans for sweeping constitutional reforms.

The South American country's National Electoral Council has said more than eight million people voted to grant president Maduro's ruling socialist party virtually unlimited powers with a constitutional assembly - a turnout disputed by political opponents.

Mr Johnson said the vote was "dubious" and warned that the country was turning on itself.

There were serious clashes between police and protesters on Sunday as the vote was held in the latest signs of the political unrest which has claimed scores of lives in the the oil-rich nation in recent months.

Mr Johnson said: "Venezuela stands on the brink of disaster and Nicolas Maduro's government must stop before it is too late.

"The country is turning on itself - more than 100 have died already - and democracy and basic rights are in jeopardy.

"The dubious constituent assembly vote has dramatically deepened the problems and ramped up tensions. It is time for the government to see sense and start working with the opposition on a way forward that brings the people of Venezuela back together."

Mr Maduro called the vote for a constitutional assembly in May after a month of protests against his government, which has overseen Venezuela's descent into a devastating crisis during its four years in power.

Plunging oil prices and widespread corruption have left the formerly prosperous nation struggling with widespread shortages of food and medicine.

The winners among the 5,500 ruling-party candidates running for 545 seats in Mr Maduro's new constituent assembly will have the task of rewriting the country's constitution and will have powers above and beyond other state institutions, including the opposition-controlled congress.

Mr Maduro said he wanted the assembly to strip opposition MPs and governors of constitutional immunity from prosecution - one of the few remaining checks on ruling party power.

Declaring the opposition "already has its prison cell waiting", Mr Maduro added: "All the criminals will go to prison for the crimes they've committed."

Shadow Foreign Office minister Liz McInnes said: "We mourn all those who have been killed and injured in the protests leading up to this election, and we urge everyone in Venezuela - on all sides - to end the bloodshed immediately.

"In particular, we urge the government of Venezuela to recognise its responsibilities to protect human rights, free speech and the rule of law.

"The outcome of this election cannot be treated as a mandate for a further escalation of repression, division and violence."

The Labour MP added that Mr Maduro should respond "personally to the legitimate concerns" of the international community about the "increasingly authoritarian nature" of his rule and the "growing hardship" facing his people.