Jailed political activists Alaa Abdel-Fattah and his sister Sanaa have been allowed to visit their sick father, prominent human rights lawyer Ahmed Seif El-Islam.

According to Seif's daughter Mona, he suffered a cardiac arrest for few minutes on Friday before he was given CPR. He remains unconscious though.

"We tried not to talk a lot about the issue because around ten days ago we submitted a request to the public prosecutor to allow Alaa and Sana to visit dad in the ICU and we wanted to keep it low [key] to increase the chances for the visit to happen," said Mona Seif via her Facebook account on Saturday.

She added that after midnight, Sanaa was brought by security forces to the hospital to visit her father and 30 minutes later she left the hospital and her brother was brought in for a visit.

Sanaa is currently on trial for violating the protest law while her elder brother Alaa was sentenced to a 15-year jail term over similar charges. However, he is currently undergoing a retrial.

"In spite of all the pain, thank God they saw him," added Mona Seif.

The visit was made possible by the efforts of lawyers and members of the National Council for Human Rights, she said.

"I have no idea what will happen to our father's condition, or when he will, or if he will, become conscious again, but I am sure he feels us and the love surrounding him ... and I am sure he heard Sanaa and Alaa when they spoke to him."

Seif El-Islam is a long-time human rights defender and anti-torture advocate who has been detained by authorities several times since the 1980s.

In 1999, he, along with other human rights advocates in Egypt, founded the Hisham Mubarak Law Centre.