Egypt's president has told a US broadcaster his country and Israel are cooperating against armed groups in the Sinai Peninsula, a potentially damaging acknowledgement that could explain a request that the network not air the interview.

Excerpts from the interview released by CBS over the weekend also showed President Abdel Fattah el-Sisi denying there are political prisoners in Egypt, where he has overseen one of the largest crackdowns on dissent in the country's modern history since the overthrow by the military, then led by him, of a divisive president.

CBS, which will air the full interview Sunday on its show 60 Minutes, said it has rejected a request by the Egyptian government not to show it. It did not say which part of the president's comments Cairo objected to, but the cooperation with Israel, with whom Egypt has a 1979 peace treaty, appears to be the most contentious part.

Egypt's military last year denied press reports that it and Israel were cooperating against insurgents in northern Sinai, a region of rugged mountains and desert bordering Israel and the Gaza Strip where Egyptian security forces have for years battled the fighters, now led by the Islamic State of Iraq and the Levant (ISIL) group.

According to the excerpts, el-Sisi was asked if his country's cooperation with Israel was the closest ever between the two countries. "That is correct... We have a wide range of cooperation with the Israelis," he responded.

Israeli officials have publicly praised security cooperation with el-Sisi's Egypt, which has successfully secured Israel's permission to deploy troops, artillery, and helicopter gunships close to the Israeli border to fight the armed groups in contravention of the peace treaty's limitations on the number of troops and weapons Egypt can have in the region.

El-Sisi has, since taking office in 2014, met at least twice with Israeli Prime Minister Benjamin Netanyahu. Their meetings have received little media attention in Egypt, a country where most people still view their neighbour as their sworn enemy and where trade unions and most political parties are vehemently opposed to the "normalisation" of relations with Israel.

What detentions?

In the interview, Sisi questioned a recent Human Rights Watch report that Egypt was detaining 60,000 political prisoners.

"I don't know where they got that figure. I said there are no political prisoners in Egypt. Whenever there is a minority trying to impose their extremist ideology we have to intervene regardless of their numbers," he told CBS.

El-Sisi has in the past claimed that everyone in detention is facing legal proceedings for a specific crime committed, but rights activists complain of long detentions without charges - as long as two years or more in some cases - trials that don't observe the letter or the spirit of the law and judges more concerned with "protecting the state" than enforcing the law.

Al Jazeera journalist Mahmoud Hussein was arrested in December 2016 as he returned home to visit his family. Hussein has been held in an Egyptian prison without charge for 743 days.

The detentions are part of a large crackdown on dissent that includes tight control of the media, placing draconian restrictions on rights groups and reversing most of the freedoms gained by a 2011 uprising against autocrat Hosni Mubarak.

El-Sisi won a second, four-year term in office last year after running virtually unopposed.