The Public Order Ministry rejected on Sunday accusations that four suspects arrested during bank robberies in Velvento, northern Greece, on Friday had been abused while in custody.

SYRIZA and Democratic Left issued statements expressing concern about the possibility the alleged bank robbers had been tortured after the police released photos of the suspects which showed them with heavy bruises.

Some of the photos also appeared to have been doctored to disguise injuries to the suspects, two of whom have been linked to the Conspiracy of the Cells of Fire urban guerrilla group.

“The torture of detainees is a disgrace for the Greek state,” said SYRIZA. “It is very difficult for even the leadership at the ministry to think this is an isolated incident,” added the opposition party with reference to a recent Guardian report on police abuse.

SYRIZA called for judicial authorities to investigate the matter.

Democratic Left (DIMAR), a junior partner in the three-party coalition, also called for a probe.

“Terrorism is the enemy of society and democracy must confront it decisively,” said DIMAR. “However, democracy does not exact revenge. An investigation and explanations are needed with regard to the faces that have been deformed due to beatings.”

The Public Order Ministry, however, denied that the suspects, aged 20 to 24, had been abused.

“If SYRIZA or anyone else has evidence regarding the torturing of detainees and not injuries to terrorists resulting from a confrontation and their resistance, they should have already submitted it to the justice system rather than just issue statements,” said the ministry.

It referred to accusations that there was a general problem in the Greek police regarding the abuse of suspects as “hair-raising and dangerous.”

Police in western Macedonia also issued a statement insisting that only “necessary force” had been used to apprehend and disarm the suspects, who had allegedly carried out two armed robberies and taken a hostage.

The police also said that the alleged robbers had been armed with Kalashnikov assault rifles, a Scorpion submachine gun, handguns and a shotgun.

Police issued a statement on Sunday saying they have matched the fingerprints of one of the suspects with those found at two properties, one in the Athens neighborhood of Kallithea and one in Volos, central Greece, that were used as hideouts for Conspiracy of the Cells of Fire.

Two of the four men detained on Friday were the subject of arrest warrants issued in 2011.