An operation was launched Sunday in Istanbul and other provinces against people suspected of being affiliated with what the Turkish government describes as the "parallel state," an alleged group of bureaucrats embedded in the country's institutions, including the judiciary and the police.
Speaking in Kocaeli on Monday, Erdogan said the EU had no authority to meddle in the internal affairs of Turkey, in response to criticism from European leaders.
"No one has authority to meddle into the steps taken by the Turkish security. The EU should keep its opinions to itself," the president said.
He made the remarks during a speech at the inauguration ceremony of a new refinery facility by the Turkish Petroleum Refineries Corporation, known as the TUPRAS.
Erdogan responded to comments by Federica Mogherini, the European Commission’s High Representative for Foreign Affairs and Johannes Hahn, Commissioner for European Neighborhood Policy and Enlargement Negotiations, who described Sunday’s police crackdown in Turkey as going against European values.
Referring to the outlawed Kurdistan Workers' Party, Erdogan said: "They should look at their own double standards in failing to punish members of terrorist groups like the PKK."
He also criticized Germany for its alleged failure to conclude cases against PKK members in the country.
The Kurdistan Workers' Party or the PKK is listed as a terrorist organization by Turkey, the U.S. and the EU.
Turkey is currently engaged in a "solution process" with the outlawed group to end more than three decades of fighting that has so far claimed more than 40,000 lives.
Erdogan also reminded the EU for its failure in extraditing Fehriye Erdal, the alleged murderer of Turkish businessman Ozdemir Sabancı in 1996. Erdal is a member of Turkey's outlawed Revolutionary People’s Liberation Party-Front.
"Those who seek to return the old Turkey are taking their answers. The violence and treason will not be left unanswered," Erdogan said.
Later, at another event in Kocaeli, Erdogan accused Ekrem Dumanli, the editor-in-chief of Turkey’s Zaman daily, who is among the detainees, of "showing off."
The president said that the fact that the Zaman daily claimed it knew about the Sunday police operation beforehand goes to show that they were, in fact, part of an illegal organization.
"They said they were informed about the operation before it started. They started waiting at the building of their newspapers, with the hope that they would avoid detention there. They are well aware of the scope of their treason; that's why they are showing off," he said.
The police operation was launched Sunday in 13 Turkish provinces, which resulted in the detention of more than 20 local media figures and police officials.
Erdogan has vowed to hold accountable the U.S.-based cleric Fethullah Gulen and members of his so called Gulen movement on numerous occasions. The government has described the movement and its supporters as the "parallel state" since late 2013.
In December 2013, an anti-graft probe targeted several high-profile figures, including the sons of three former government ministers and leading Turkish businessmen.
Since then, hundreds of police officers have been detained on charges of eavesdropping on Turkey's top officials, disclosing highly-sensitive information, forming and belonging to an organization to commit crime, violating privacy, illegally seizing personal information and forgery of official documents.
In his speech on Monday, the president also highlighted developments in the Turkish economy.
"We will not bow to these circles conducting systematical smear campaigns on the Turkish economy. Despite their manipulations, the Turkish economy continues to grow and democracy develops," Erdogan said.
He praised the Turkish corporation TUPRAS's newly-opened $3 billion fuel-oil recycling facility in Kocaeli.
"This investment will contribute to employment and exports in Turkey, and help make Turkey an energy hub and reduce the $1 billion current account deficit," Erdogan said.
Turkey is an increasingly important energy hub and transit route for oil and natural gas from Russia and Middle East to Europe.
Early December, Putin announced plans of a new pipeline project to pass through Turkey's northwestern Thrace region and a natural gas hub on the Turkish-Greek border to replace the South Stream natural gas pipeline, which was initially planned to pass through Bulgaria to Europe.