A proposed new Egyptian constitution has been backed by 98.1% of people who voted in a referendum, officials say.

Turnout was 38.6% of the 53 million eligible voters, the election committee said.

The draft constitution replaces one introduced by Islamist President Mohammed Morsi before he was ousted.

The referendum is being seen as a vote on the legitimacy of his removal and of the army, which toppled him in July last year.

The vote, which took place on Tuesday and Wednesday but was boycotted by members of the Muslim Brotherhood, the Islamist movement from which Mr Morsi comes and which wants to see him returned to office.

Several people died in violence involving Mr Morsi's supporters on the first day of voting.

There were further clashes with the security forces on Friday in which four people died, the Health Ministry said.

Huge security operation

Election Commission head Nabil Salib called the vote an "unrivalled success" with "unprecedented turnout", AP news agency reported.

Later on Saturday, US Secretary of State John Kerry urged Egypt "to fully implement those rights and freedoms that are guaranteed in the new constitution".

He said in a statement: "Egypt's turbulent experiment in participatory democracy the last three years has reminded us all that it's not one vote that determines a democracy, it's all the steps that follow."

He added: "The interim government has committed repeatedly to a transition process that expands democratic rights and leads to a civilian-led, inclusive government through free and fair elections. Now is the time to make that commitment a reality."

A constitutional referendum held in 2012 while Mohammed Morsi was in power but boycotted by secularists saw a turnout of 33%, with 64% of voters approving the document.

The new proposed constitution was drafted by a 50-member committee that included only two representatives of Islamist parties.

Critics say the document favours the army at the expense of the people, and fails to deliver on the 2011 revolution that led to the fall of Hosni Mubarak.