Fears are mounting for the safety of four Irish citizens believed to have been in a besieged Egyptian mosque stormed by troops as violence escalates in the country.

The three sisters and their teenage brother are the siblings of Hussein Halawa, the Imam of the Islamic Cultural Centre in Clonskeagh in Dublin.

Their family back in Ireland are desperately trying to make contact with them after Egyptian security forces stormed the Al Fateh mosque in Cairo.

Their sister Nasaybi Halawa has told the Irish Times that the family are ‘extremely concerned’ for their well being.

The report says hundreds of people in the mosque had sought refuge from violent clashes on Friday during the ‘Day of Rage’ protests organised by the Muslim Brotherhood.

The family believe siblings Omaima (21), and Fatima (23) have been detained by the Egyptian authorities but their current whereabouts are unknown.

Somaia, 27, and 17-year-old brother Ibrihim are also missing but the family are unsure if they were arrested at the mosque or fled.

Nasaybi Halawa told the Trish Times: “The last time I talked to my sister was about 1pm this afternoon.

“They had taken her mobile phone but she managed to borrow one. All the while they (security forces) were harassing her and she was screaming and crying.

“We are trying to cope. We are trying to be strong so we can do something for them. We have a hope that everything will be fine.

“We do not know anything about them. We do not know where they have been taken. We do not know if they are in one of the police stations in Cairo or somewhere else. We don’t even know where to start looking.”

The Halawa family have lived in Dublin for the past 18 years and travel to Egypt every summer to visit family.

Hussein Halawa - the Imam of the Islamic Cultural Centre in Clonskeagh, is still in Dublin but their mother travelled to Cairo two weeks ago.

Nasaybi Halawa said her mother and uncles have been in contact with a lawyer in Cairo and are beginning a search of the city’s police stations.

She added that conditions inside the mosque were ‘austere and traumatic’.

She said: “They were inside for 18 hours without food and water. They had to drink from a fountain which was not meant for drinking.

“My brother, who is under 18 years of age was in the same place as dead bodies. They had been running from gunfire and the mosque, as a holy place should be respected. Is that a crime now?”

The siblings has taken refuge in the mosque on Friday as violent clashes between supporters of ousted president Mohammed Morsi and the security forces killed scores of people in the Egyptian capital.

Officials from Ireland’s Department of Foreign Affairs are liaising with authorities in Egypt.

A spokesman said: “We are in ongoing contact with the Egyptian authorities in relation to the safety and well-being of all Irish citizens involved. We are also involved with the family in Dublin.”