Wael Abbas is a blogger and democracy activist
A human rights organisation in Egypt has accused the interior ministry of manipulating the legal system to target a blogger who exposed police brutality.
The Arabic Network for Human Rights Information said Wael Abbas had been sentenced to six months in jail in a case that had already been closed.
A Cairo appeals court cleared him last month of damaging an internet cable.
But he was then convicted of "providing a telecommunications service to the public without permission".
The Arabic Network for Human Rights Information said it would take legal action against Mr Abbas's neighbour, the brother of a police officer, whom it suspects of helping the authorities to persecute the blogger.
Mr Abbas's new conviction and sentence were also condemned by the New York-based Committee to Protect Journalists (CPJ).
The CPJ quoted Mr Abbas's lawyer, Rawda Ahmed, as saying that neither he nor his client had been informed of the new legal action, and his client remained a free man on Friday.
'Twisted legal path'
The blogger was sentenced in November to six months in prison and a fine of 500 Egyptian pounds ($90, £60) on the charge of damaging an internet cable.
This conviction was thrown out by the appeals court in February on the grounds that the charges were unfounded.
But Egypt's Economic Court sentenced Mr Abbas on Wednesday to the same jail term and fine on the unauthorised telecommunications charge.
"This sentence was issued through a twisted legal path and reveals an invisible hand manipulating the case," Mr Ahmed said.
"The case was closed and we already proved to the courts that the charges brought against my client were fabricated."
Condemning the new conviction, the CPJ's Middle East and North Africa Program Coordinator, Mohamed Abdel Dayem, called on the Egyptian judiciary to overturn it.
"To manufacture one charge after another until one finally sticks makes a mockery of the law," he said.
Mr Abbas is described by the CPJ as a leading voice in an anti-torture campaign in Egypt, posting a number of videos on his blog that revealed abuse of people in official custody.