Egypt is investigating jailed ex-president Mohamed Mursi in connection with documents that judicial investigators say were leaked to the Qatar-based Al Jazeera satellite news channel, said security sources.

Relations between Qatar and Egypt have been tense since mid-2013 when then-army chief Abdel Fattah al-Sisi toppled the Islamist Mursi after mass protests against his rule. Qatar supported Mursi and his Muslim Brotherhood.

Mursi is being questioned in connection with his secretary's daughter who is suspected of leaking sensitive security documents to Al Jazeera, the security sources said.

"The security officials recorded a phone call between the daughter of Mursi's secretary and an Egyptian journalist who works for Al Jazeera in which the woman said she wants to give him important security documents," said a security official.

"Mursi is being investigated to find out if he knew about this phone call or if he had leaked these documents to his secretary," the official added. "We also know that the woman had been trying to send the documents to the Qatari intelligence."

The satellite channel said in response: "Any information Al Jazeera receives is handled with the highest standard of journalistic ethics. We do not therefore comment on sources, or pass information to governments."

Al Jazeera has been banned from Egypt over what Cairo says is its support for Islamists. Al Jazeera says it aims for balanced news coverage airing all points of view.

Sisi went on to election as president while Mursi has been jailed on suspicion of inciting violence and various other offences. He and other Brotherhood leaders could face a life sentence or the death penalty if convicted.

Egyptian security forces killed hundreds of Muslim Brotherhood supporters during street protests and thousands of others have been jailed, and Egypt's oldest Islamist movement has been branded a terrorist group and outlawed.

The Brotherhood renounced violence as a means of political change decades ago and has denied any role in recent bloodshed.

Egypt, the biggest Arab state, is deeply suspicious of Qatar and anyone who supports the Brotherhood, once Egypt's most organised political movement but long isolated by a military-backed authoritarian leaders until the 2011 popular uprising.

Egypt has jailed three Al Jazeera journalists for up to 10 years on charges of aiding "a terrorist group" by broadcasting misinformation that harmed national security. Al Jazeera has said the charges are baseless.-Reuters