Egyptian President Mohamed Mursi signed into law a new constitution shaped by his Islamic allies, a bitterly contested document which he said would help end political turmoil and allow him to focus on fixing the economy.

The new constitution, which the liberal opposition says betrays Egypt’s 2011 revolution by dangerously mixing religion and politics, has polarised the Arab world’s most populous nation and prompted occasionally violent protest on the streets.

In his first address to the nation of 84 million since the adoption of the new constitution, Mursi said it was time for all political forces to put aside their differences and start working together to bring stability.“I will make all efforts, together with you, to push forward the economy which faces huge challenges and has great opportunities to grow,” Mursi said in a televised speech.

The presidency announced on Wednesday that he had formally approved the constitution the previous evening, shortly after results showed that Egyptians had backed it in a referendum.The text won about 64 per cent of the vote, paving the way for a new parliamentary election in about two months.

The charter states that the principles of sharia, Islamic law, are the main source of legislation and that Islamic authorities will be consulted on sharia – a source of concern to the Christian minority and others.The referendum result marked yet another electoral victory for the Islamists since veteran autocrat Hosni Mubarak was toppled in 2011, following parliamentary elections last year and the presidential vote that brought Mursi to power this year.

Mursi’s government, which has accused opponents of damaging the economy by prolonging political upheaval, now faces the tough task of building a broad consensus as it prepares to impose austerity measures.In his speech, Mursi said he would introduce incentives to make Egypt a more attractive place for investors and considered making changes in the cabinet as part of his plan.“The coming days will witness, God willing, the launch of new projects … and a package of incentives for investors to support the Egyptian market and the economy,” he said.