Egyptian President Abdel Fatah al-Sisi is to declare a three-month state of emergency after Isis attacks on two Coptic churches kill at least 43 people.

Twin bombings during packed services at churches in the cities of Alexandria and Tanta came as worshippers were celebrating Palm Sunday – the start of the most holy week in the Christian calendar.

The first attack in the St George's church in Tanta, north of Cairo in the Nile Delta, killed 27 people and wounded at least 78 more.

The second explosion came later at St Mark's Cathedral in Alexandria – the historical seat of Christianity in Egypt – killed a further 16 and wounded 31 just after the Coptic Pope, Tawadros II, finished services.

Mr Sisi did not say what legal measures he would use to invoke the state of emergency but under the Egyptian constitution a parliamentary majority must vote in favour of it.

He accused countries he did not name of fuelling instability in Egypt, saying "Egyptians have foiled plots and efforts by countries and fascist, terrorist organisations that tried to control Egypt".

The former army chief previously declared a state of emergency in the months following the ousting of the democratically elected President Mohamed Morsi in 2013 when his supporters staged mass demonstrations that descended into violence.

Ever since Mr Sisi's government has cracked down on dissent and declared Mr Morsi's party, the Muslim Brotherhood, a terror group.

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Egypt's Interior Ministry said a suicide bomber had tried to storm the entrance of St Mark's but was stopped by police. Three of the victims in the Alexandria attack were police officers.

Roman Catholic Pope Francis denounced the attack which came a week before a scheduled trip to Cairo.

He expressed his "deep condolences" to his "brother" Pope Tawadros – who was unharmed in the blast – and the Coptic church. He said he was praying for the dead and the wounded as he marked Palm Sunday in Rome.

He asked God ''to convert the hearts of those who spread terror, violence and death, and also the hearts of those who make, and traffic in, weapons".

Isis later claimed responsibility for both attacks with its propaganda arm, Amaq, claiming the bombers had used suicide vests.

The group had recently warned it would step up attacks on the Egyptian Christian community which makes up around 10 per cent of the population.

A local Isis affiliate group claimed a suicide bombing at a church in Cairo at the end of last year which killed around 30 people, mostly women, as well as a string of killings in the restive Sinai Peninsula which has caused hundreds of Christian to flee.

The country has struggled with the growing problem of Islamic extremism since the military coup.

In 2015 Isis blew up a Russian metrojet flight over Sinai killing all 224 people on board and wrecking the country's tourism industry.