Giza prosecutors have ordered the arrest of 15 people implicated in the murder of four Egyptian Shias in attack by Sunni Muslims in a Giza village on Sunday, an incident which has heightened sectarian tensions in an already polarised country.

Prosecutors have discovered the identities of some perpetrators of the vigilante murders, a security source told state news agency MENA.

Four Egyptian Shia Muslims were killed in a mob attack, allegedly led by Salafist sheikhs, in the town of Zawyat Abu Musalam in Giza governorate on Sunday afternoon.

Residents surrounded a house of a prominent Shia local after being informed he was hosting a religious gathering, beating the guests and setting the house on fire, according to reports.

Head of the Shia Current in Egypt, Mohamed Ghoneim, condemned the murders, which he described as "lamentable" and "traumatic."

In a phone-in with Dream satellite TV channel on Monday, the Shia leader blamed the incident on what he perceived as the growing extremism of religious channels and pragmatic "political calculations."

He went on to cite what he sees as attempts by the Muslim Brotherhood, the group from which President Morsi hails, to 'please' Salafists, in order to win their backing in advance of planned anti-government protests on 30 June.

Ghoneim went on to ask for international protection for Shias in Egypt, vowing to launch a campaign to this end.

Inflammatory anti-Shia rhetoric by some hardline Islamist clerics has been on the rise recently, apparently as a result of the growing conflict in Syria, as well as a recent thaw in Egypt-Iran ties.

There is no official tally of the number of Shia Muslims in Egypt. Analysts believe adherents to the Shia faith in Egypt number between 500,000 and one million.

While some critics blame the Salafist-oriented Nour Party for igniting anti-Shia sentiment, the party has rejected any suggestion of involvement.

"We have warned the regime about looming sectarian friction, amid acts of insulting and demonising the Sahabah [the companions of the Prophet Mohamed] which will shock the fabric of Egyptian society, but it paid no heed," party spokesman Nader Bakkar said via Twitter late on Sunday.

Dogmatic divisions between Shia and Sunni Muslims include differences over the place of the Prophet Mohamed’s companions with each side favouring some over others.

Bakkar said, however, that his party "does not accept the shedding of Egyptians' blood and dragging them in such an appalling way."

The hardline group, as well as its ideological parent organisation the Salafist Call, has been largely blamed for the rising extremist rhetoric against Shia Muslims. Posters bearing the logo of both the Salafist Call and the Nour Party have recently appeared in a number of Egyptian cities demonising the sect and its followers.

Salafist parliamentarians have also expressed misgivings over the restoration of diplomatic ties with Shia-majority Iran, and plans to encourage Iranian tourists to visit Egypt. One MP in May went as far as branding Shiites "more dangerous than naked women" and a threat to national security.

The Salafist Call, however, dismissed on Monday attempts to link it to the incident, asserting its precept severely condemning violence.

Meanwhile, the Muslim Brotherhood was also quick in denouncing the killing.

"Bloodletting of Egyptians is prohibited, a Muslim or Christian...a Sunni or Shia, it is prohibited," said Essam El-Erian, deputy head of the Muslim Brotherhood's Freedom and Justice Party in a statement posted on his Facebook page.

Whoever takes part in inciting murder or promoting hate speech is taking part in a heinous crime, he added.

President Mohamed Morsi and the Muslim Brotherhood have recently thrown their weight behind a call for jihad in Syria by fellow Sunni Islamists across the Middle East.

The already embattled president has been censured by his opponents for failing to curb sectarian utterances against Shia Muslims made by his Islamist backers at a Syria solidarity conference last week, during which he announced that Egypt would cut diplomatic ties with Damascus.

The president’s office said in a Monday statement in response to the mob killings that "the state will not be lenient with anyone who tampers with Egypt's security or the unity of its people."

Prime Minister Hisham Qandil also condemned the incident as contradicting all "religious doctrines."

The Egyptians against Religious Discrimination, an independent group fighting religious sectarianism in Egypt, denounced in its statement on Monday what it described as a series of sectarian crimes under the Muslim Brotherhood's rule.

Morsi’s rule “opened the door for sectarian strife between Egyptians,” claimed the statement.