IZMIT, TURKEY  - Turkish President Tayyip Erdogan said on Monday that weekend raids on media outlets close to a US-based Muslim cleric were part of a necessary response to “dirty operations” by political enemies, and dismissed European Union criticism of the moves.

The raids on the Zaman daily and Samanyolu television mark an escalation in Erdogan’s battle with former ally Fetullah Gulen, with whom he has been in open conflict since a graft investigation targeting his inner circle emerged a year ago.

Erdogan accuses Gulen of establishing a ‘parallel’ structure in the state through his supporters in the judiciary, police and other institutions, while wielding influence through the media. The cleric denies any ambition to overthrow Erdogan.

Erdogan Monday launched a stinging attack on the European Union over its criticism of police raids on opposition media, bluntly telling Brussels to “mind its own business”. The European Union led the criticism with EU foreign policy chief Federica Mogherini and Enlargement Commissioner Johannes Hahn condemning the raids as “incompatible with the freedom of media”.

But Erdogan lashed out at the criticism and indicated that he did not care what impact the arrest would have on Turkey’s long-stalled membership bid to join the EU.

“The European Union cannot interfere in steps taken... within the rule of law against elements that threaten our national security,” Erdogan said in a televised speech in the western Turkish city of Izmit. “They should mind their own business,” he added, in his first comments after Sunday’s raids. “I wonder if those who keep this country at the EU doorstep for 50 years know what this step means?” Erdogan said, referring to the arrests. “When taking such a step we don’t care what the EU might say, or if the EU is going to accept us.”

Among a total of at least 27 people arrested in the nationwide raids were Ekrem Dumanli, the editor-in-chief of the Zaman daily newspaper which is closely linked to Gulen and Hidayet Karaca, the head of the pro-Gulen Samanyolu TV (STV).

Also detained were staff including a producer, a director and scriptwriters on popular TV drama series Tek Turkiye (One Turkey) broadcast on STV. The director and two scriptwriters for the TV series were released overnight.

The Zaman daily reported that two more detainees were set free on Monday, including the newspaper’s columnist Ahmed Sahin. The other suspects were still being questioned by the Istanbul police.

The state Anatolia news agency said chief public prosecutor Hadi Salihoglu ordered the arrests on charges of forgery, fabricating evidence and “forming a crime syndicate to overtake the sovereignty of the state”.

Several police were also detained, including Tufan Erguder and Mutlu Ekizoglu, former heads respectively of the Istanbul anti-terrorism and organised crime police departments. US State Department spokeswoman Jen Psaki said Washington urged Turkey to make sure the raids did not violate its “own democratic foundations”. US-based rights group Freedom House said the arrests were “a threat to free expression in Turkey and to anyone critical of its government”.

Press freedom group the International Federation of Journalists (IFJ) said they were “appalled by this brazen assault on press freedom and Turkish democracy”.

The Zaman newspaper itself headlined, “Black day for democracy,” in black fonts. Thousands of journalists and supporters had gathered at the Zaman headquarters Sunday to give Dumanli a hero’s send-off as he was led away by plain-clothes police.

A defiant Erdogan pledged to pursue what he called “enemies of the state” at home and abroad and portrayed the raids as part of “normalisation process”.

“We know the dimension of the crimes they have committed,” he said in a second speech. “Nobody should shed crocodile tears.”

Markets reacted with anxiety to the news as the domestic currency lira lost 1.42 percent in value against the dollar - the lowest since January this year.

Erdogan has accused Gulen, who is based in Pennsylvania, of running a “parallel” state using influence in the police, judiciary, media and schools.

The Turkish government has repeatedly asked Washington to extradite Gulen, 73, but to no avail.

The crackdown came almost a year to the day after Erdogan’s government was rocked by stunning corruption allegations that the authorities denied and blamed on Gulen.

The corruption probe - opened on December 17, 2013 - saw the arrests of dozens of leading businessmen and political figures close to Erdogan, then prime minister.

The last months have seen successive raids against suspected pro-Gulen elements in the police force, but this was the first time media had been so directly targeted. They also come ahead of June’s legislative elections.