Egyptian authorities have arrested Ismail Alexandrani, a prominent journalist and expert on jihadist movements in Sinai, on charges of publishing false information and belonging to the banned Muslim Brotherhood, his lawyers said Tuesday.

Earlier, Alexandrani's wife, Khadija Gaafar, said the 32-year-old had been arrested in the Red Sea resort of Hurghada on Sunday when he returned from Berlin.

Thousands of activists, as well as several journalists, have been detained since then army chief and now President Abdel Fattah al-Sisi overthrew his Islamist predecessor, Mohamed Morsi, in 2013.

"They then took him for interrogation to Cairo," Gaafar said. "I don't know what accusations have been made against him. I didn't meet him, nor have I spoken to him since his arrest. His lawyers are with him."

A security official confirmed Alexandrani's arrest but refused to comment on any charges.

Defence lawyer Ahmed Abdel Nabi said Alexandrani had been ordered held for 15 days.

He was charged with "belonging to an illegal organisation, the Muslim Brotherhood" of deposed president Morsi, and of publishing "false information with the aim of damaging the national interest and disturbing the peace."

Another lawyer representing Alexandrani, Mohammed al-Baqer, said the journalist would be questioned again on Thursday.

In New York, Human Rights Watch issued a statement referring to him by a variant of his name, Iskandrani.

His arrest "is deeply disturbing and fits a pattern of Egyptian security agencies arresting people whose writings don't conform to official views," said Joe Stork, HRW's deputy Middle East director.

For his part, Abdel Nabi said the affair "sends a very negative message to journalists, encouraging them to self censorship when their opinions diverge from those of the authorities."

An expert on jihadist movements in North Sinai, where security forces are fighting a swelling insurgency led by the Islamic State group, Alexandrani had been to Germany to deliver lectures on the political situation in Egypt, Gaafar said.

Alexandrani is also known for his anti-regime writings and for criticising the military's role in politics.

He is the second journalist to be detained in recent weeks after the military held prominent rights defender and reporter Hossam Bahgat for a day last month.

Human rights groups accuse Sisi of installing a repressive regime that has arrested thousands of activists, mostly Islamists, but also leftists and journalists.

Morsi's ouster unleashed a bloody crackdown on protesters that killed hundreds of demonstrators, while militants launched an insurgency that killed hundreds of policemen and soldiers.

Three reporters with Al-Jazeera were detained in 2013 and later convicted of fabricating "false" news in support of the Brotherhood.

Their trial sparked international criticism led by the White House and the United Nations.

One of the Al-Jazeera journalists, Australian Peter Greste, was deported and the other two, Canadian Mohamed Fahmy and Egyptian Baher Mohamed, were eventually pardoned and released.