BERLIN (Reuters) - German politicians accused Chancellor Angela Merkel at the weekend of making Europe overly dependent on Turkey in the migrant crisis, leaving the bloc vulnerable to blackmail by President Tayyip Erdogan.

Slideshow ( 2 images )

Turkey, refusing to bow to European Union demands to rein in its broad anti-terror laws, said on Friday talks on a deal to provide visa-free travel in return for stopping illegal migrants reaching the EU had reached an impasse and the bloc must find a “new formula” to salvage the agreement.

Merkel, whose popularity has suffered due to her liberal migrant policy that saw Germany take in more than one million migrants last year, had spearheaded EU efforts to secure the deal, signed in March.

While the numbers of migrants have dropped sharply this year, Merkel continues to attract criticism from her conservative allies in Bavaria as well as the anti-immigrant Alternative for Germany (AfD).

“I’m not against talks with Turkey but I think it’s dangerous to become so dependent on Ankara,” said Horst Seehofer, leader of the Christian Social Union (CSU), the Bavarian sister party to Merkel’s Christian Democrats (CDU).

Seehofer told Welt am Sonntag (WamS) that the deal with Turkey had helped boost support for AfD, which is currently polling at up to 15 percent.

Sahra Wagenknecht of the opposition far-left Linke party told the same newspaper Merkel had essentially negotiated the deal without involving her European partners.

“The chancellor is therefore responsible for Europe having become vulnerable to being blackmailed by the authoritarian Turkish regime and for Erdogan feeling noticeably strengthened to crush human rights underfoot,” she said.

Cem Oezdemir, co-leader of the Greens party and the son of Turkish immigrants, also told WamS the deal had put Europe at risk of being blackmailed and said Merkel was largely to blame.

While the EU is desperate for the deal to succeed, it also insists that Turkey meet 72 criteria, including anti-terror laws which it says Turkey uses to stifle dissent. Ankara says it needs sweeping legislation to fight Kurdish insurgents and Islamic State.

Merkel is due to attend the World Humanitarian Summit in Istanbul on May 23 and there are plans for bilateral talks with other leaders in attendance, her spokesman said on Friday.

Members of the Social Democrats (SPD), Merkel’s junior coalition partner, also expressed concern.

Carsten Schneider told WamS Merkel had made Erdogan the key to her refugee policy and if he stopped cooperating, “the extent of Germany’s isolation in Europe will become clear again”, while Thorsten Schaefer-Guembel said Merkel should not “kowtow” to Erdogan.

But SPD Foreign Minister Frank-Walter Steinmeier told Tagesspiegel newspaper Turkey was still the key country for migration to Europe, adding: “We need to cooperate to some extent if we want to avoid the circumstances we had last year.”

Merkel has drawn heavy criticism for allowing German prosecutors to pursue a case against a German comedian at the Turkish leader’s behest. The comic had recited a sexually crude poem about Erdogan.