Egyptian authorities have arrested seven people over a suicide bombing at a police station north of Cairo that left 16 dead.
Mohammed Ibrahim, the interior minister, produced on Thursday what he said was a confession by the son of a senior member of the Muslim Brotherhood they arrested over the blast in the city of Mansoura.
Ibrahim aired a recording in a news conference said to be of Yahia Mongi, son of a Brotherhood politician, in which he said he joined the Sinai peninsula-based Ansar Beit al-Maqdis, or Champions of Jerusalem, group.
The minister said that Mongi was part of a seven-member cell that carried out a suicide bombing of the provincial security headquarters last month.
The group Ansar took responsibility for the blast, as well as other attacks.
The charge that the Brotherhood has links to Ansar Beit al-Maqdis is central to the government's case for labelling the group associated with ousted President Mohammed Morsi as a terrorist organisation.
The confession was the first purported piece of hard evidence produced by authorities to make the link.
Alexandria jails secular activists
Human rights advocates say police frequently use torture and other means of coercion to produce confessions, relying on them in lieu of other evidence to convict defendants in both ordinary criminal and security trials.
The Brotherhood denies that it practices violence and accuses police of plotting the attacks to find a pretext for a heavier crackdown on its members.
The news conference came after a court set January 28 as the opening date for Morsi's trial along with 130 others in connection to a 2011 jailbreak. It is the third set of charges that Morsi faces.
Ibrahim said Mongi's role was surveillance and hosting the Ansar's leader.
He listed names of Muslim Brotherhood members alleged to have crossed to the Gaza Strip and received training from Hamas, which rules the territory.
The minister said they carried out other attacks, including shooting anti-Morsi protesters, when they returned to Egypt.
Ibrahim said the group opened channels with Hamas, an offshoot of the Muslim Brotherhood, after the country's 2011 uprising, which brought down autocratic leader Hosni Mubarak.
The minister said the Palestinian group provided logistical support training and developed technology such as devices to jam planes' detection systems.
He did not provide any evidence for the claims of training and support.
A spokesman from Hamas, Sami Abu Zuhri, denied the accusations and called it an "attempt to mislead the Egyptian public and export the internal Egyptian crisis".
Meanwhile, a court in the Mediterranean port city of Alexandria sentenced seven secular-leaning activists to two years in prison on charges related to a protest.