Mohamed Sultan, the Egyptian-American who has been on a hunger strike for over 130 days to protest his continual detainment, has been transferred to a hospital for medical care, the interior ministry said on Tuesday.

The ministry's statement said that Sultan had been transferred to Qasr Al-Aini Hospital due to "the medical reports issued by the forensics committee assigned by the general prosecution to follow his case".

The statement added that Sultan continues his hunger strike despite all advice that he break it.

The Freedom for the Brave campaign – a grassroots movement calling for the release of all political detainees in Egypt – also released a statement on Tuesday confirming that Sultan had been transferred to the same hospital and was now in intensive care.

He is in critical condition after over 130 days of his hunger strike, the campaign said.

Earlier on Tuesday, the campaign said that the police refused to let Sultan remain in hospital, despite warnings from doctors that his health had deteriorated badly and needed care.

Sultan's brother, Omar, also said on Tuesday that he had been placed in intensive care.

"Keep him in your prayers," Omar tweeted on Tuesday afternoon.

Mohamed, 26, was arrested in August 2013 following the violent dispersal of the pro-Mohamed Morsi protest camp at Rabaa Al-Adaweya Mosque in Cairo. His family claims that he was not involved in politics and had returned to Egypt to care for his sick mother.

His father, Saleh Sultan, a leading Islamic preacher and a member of the pro-Morsi alliance, the National Authority to Support Legitimacy (NASL), was rounded up by authorities following a crackdown on the ousted president's allies and Islamist sympathisers.

Several weeks ago, Mohamed Sultan leaked a video from prison in which he called on US President Barack Obama to intervene in his case and pressure for his release.

Sultan's family has already launched a campaign in Egypt as well as the US to call for his freedom.