Update, Sunday, 5:45 a.m. EST: Greek authorities say they have found no evidence linking up to half a dozen people detained in Athens on Saturday with a foiled Islamist plot which targeted police officers in Belgium.

One of those arrested matched the description of Abdelhamid Abaaoud, the alleged leader of the cell reportedly planning the attack, but checks made in Belgium showed there was no connection to investigations into the plot, prosecutors, cited by the BBC, said.

"We have not identified anyone related to the Belgian plot from the people we detained," a senior Greek police official told Reuters.

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At least four people were arrested in Athens, Greece, Saturday for possible involvement in a foiled terrorist plot in Belgium earlier this week, a Greek police source told Agence France-Presse. But it remains unclear if the mastermind of the attack was among those apprehended. The arrests in the Pangrati district of Greece's capital followed an investigation into a jihadist cell in Belgium.

Greece’s anti-terror force is trying to determine if Abdelhamid Abaaoud, 27, the suspected leader of the jihadist cell, was among the four arrested, media reports said. Abaaoud, who goes by the name Abu Omar Soussi on jihadi missions, is a Belgian of Moroccan descent. He is known to have spent time fighting alongside the Islamic State group in Syria, the French Belgian daily La Dernière Heure reported. The newspaper also reported the FBI and the Israeli intelligence agency Mossad have been working together to track down Abaaoud.

The arrests in Greece followed a Belgian police raid on an alleged jihadist cell in Verviers in eastern Belgium Thursday night. Two militants were killed, and a third was arrested. Thirteen others in Belgium and two in France were also arrested following the raid. Belgian authorities said members of the cell planned to kill Belgian police on the streets and in police stations across the country.

Several cell phones have been seized and are now being investigated, AFP reported. While police have said the terrorist plot in Belgium has no links to the spate of attacks in Paris last week that killed 17 people, there have been investigations into whether the weapons used in those shootings had been purchased in Belgium, the Financial Times reported.

The Belgian government has also raised the terror alert level to its second-highest position, German news media Deutsche Welle reported, amid concerns young Europeans returning home after fighting alongside extremist groups in the Middle East could spark terror incidents in the country.