Egypt has extended the detention of Al Jazeera journalist Mahmoud Hussein by 45 days, pending further investigation.

The court decision on Saturday marks the fourth time Hussain's detention has been extended, and could see him held until March 15.

Though authorities decided to prolong Hussein's detention on Saturday, the announcement was only made public on Sunday.

The journalist's defence team said that while Hussein was finally able to meet his family members at Saturday's court hearing, having earlier been denied the right, he was still being mistreated and kept in an individual cell.

Hussein, an Egyptian national and journalist with more than two decades of experience, was arrested on December 20 after arriving at Cairo's international airport for a holiday.

On January 4 and 19, when his detention was due to expire, authorities extended his arrest for a period of 15 days "pending a further investigation". On February 2, authorities extended his detention by four days as they referred his case to the Giza Criminal Court.

Five days after his initial arrest, Egypt's interior ministry accused him of "incitement against state institutions and broadcasting false news with the aim of spreading chaos".

Al Jazeera rejects all charges against Hussein and urges Egypt to release him immediately.

READ MORE: Mahmoud Hussein - Freedom of expression is valuable

Hussein, who lives in Qatar's capital, Doha, joined Al Jazeera in Egypt in 2011. He moved to the network's headquarters in Qatar in 2013.

The United Nations has called on Egypt to comply with its commitment to protect freedom of expression.

In January, Stephane Dujarric, spokesman for the UN secretary-general, said: "We appeal for this case to be resolved in accordance with Egypt's own international obligations to protect freedom of expression and freedom of opinion."

Over the past few years, Egyptian authorities have arrested several Al Jazeera employees, raising concerns over media freedom in the country.

In May, a Cairo court sentenced a former editor-in-chief of Al Jazeera Arabic, Ibrahim Helal, to death, charging him in absentia with endangering national security.

Al Jazeera's Baher Mohamed, Mohamed Fahmy and Peter Greste - along with seven colleagues outside the country - were accused of spreading "false news" during their coverage of the aftermath of the military overthrow of then-president Mohamed Morsi in 2013, the year they were taken into custody.

Mohamed and Fahmy spent 437 days in jail before being released. Greste spent more than a year in prison.

The judge who sentenced the journalists said they were brought together "by the devil" to destabilise the country.