ANKARA, Turkey (AP) — Turkish President Recep Tayyip Erdogan on Tuesday directed fresh verbal attacks at the Netherlands amid their growing diplomatic spat, holding the country responsible for Europe’s worst mass killing since World War II.

In a televised speech, Erdogan referred to the massacre of some 8,000 Muslim men and boys in Srebrenica, eastern Bosnia, in 1995, and blamed a Dutch battalion of United Nations peacekeepers who failed to halt the slaughter by Bosnian Serb forces.

Erdogan said: “We know the Netherlands and the Dutch from the Srebrenica massacre. We know how rotten their character is from their massacre of 8,000 Bosnians there.”

Dutch Prime Minister Mark Rutte condemned Erdogan’s comments, calling them a “disgusting distortion of history.”

“We will not lower ourselves to this level. It is totally unacceptable,” Rutte told Dutch broadcaster RTL Z.

It was the latest in Erdogan’s war of words on the Netherlands, which prevented two Turkish ministers from holding campaign rallies in the country over the weekend. The two ministers had sought to campaign in an April 16 referendum on expanding Erdogan’s powers, courting the votes of eligible Turks in the Netherlands. Around 400,000 people with ties to Turkey live in the Netherlands.

The Turkish leader previously called the Netherlands “Nazi remnants” and also accused it of “fascism.”

Earlier, Turkey criticized the European Union for siding with the Netherlands in the row. In a statement Tuesday, the Turkish Foreign Ministry said the EU’s stance on Turkey was “short-sighted” and “carried no value” for Turkey, as well as lending “credence” to extremists.

The ministry argued that the European bloc had “ignored the (Netherlands’) violation of diplomatic conventions and the law” after Dutch authorities escorted the Turkish family affairs minister out of the country and denied the foreign minister permission to land.

The diplomatic spat between the two countries escalated swiftly with Erdogan making several Nazi comparisons with EU member states Germany and the Netherlands. The EU has called on Turkey to cease “excessive statements.”

The spat has raised concerns that co-operation between the EU and Turkey on a number of issues, such as dealing with the flow of migrants from war-torn Syria, may start to fray.

On Monday, Turkey slapped a series of political sanctions against the Netherlands, including halting political discussions between the two countries and closing Turkish airspace to Dutch diplomats. Other sanctions bar the Dutch ambassador entry back into Turkey and advise parliament to withdraw from a Dutch-Turkish friendship group.

Deputy Prime Minister Numan Kurtulmus said the sanctions would apply until the Netherlands takes steps “to redress” the actions that Ankara sees as a grave insult.

Erdogan said Tuesday there could be more sanctions but did not elaborate. Turkey’s state-run Anadolu Agency quoted Turkey Customs and Trade Minister Bulent Tufenkci as saying economic sanctions “could come to the agenda in the period ahead.”

German Chancellor Angela Merkel also backed the Netherlands in its diplomatic fight with Turkey, pledging her full support and solidarity with the Dutch and saying the Nazi jibes were unacceptable.

Erdogan responded angrily to Merkel’s support for the Netherlands, exclaiming “Shame on you!” during a television interview on Monday. On Tuesday, Erdogan described both Germany and the Netherlands as “bandit states” that were harming the European Union.

Merkel has refrained from reacting to Erdogan.

“The chancellor has no intention of participating in the race of provocations,” Merkel’s spokesman, Steffen Seibert, said late Monday. “She won’t play along. The accusations are recognizably absurd.”

Responding to another charge by Erdogan – that Germany supported terror groups in Turkey – German Interior Minister Thomas de Maiziere said his country did not need “extra tuition” from Ankara on fighting terrorism.

Also Monday, the German Foreign Ministry amended its travel advice for Turkey, noting that “elevated political tensions and protests that could also be directed against Germany” should be expected during the referendum campaign. It recommended that travelers stay away from political events and large gatherings of people.

Meanwhile, the mayor of Rotterdam said that specialized armed security forces he sent to a standoff with Turkish Family Affairs Minister Fatma Betul Sayan Kaya on Saturday night had permission to open fire if necessary.

Speaking late Monday night on a television talk show, Mayor Ahmed Aboutaleb said he sent the special armed intervention unit to the Turkish consulate amid fears that a 12-man security detail that had driven to the Netherlands from Germany with the minister could be armed.

Aboutaleb said show that it was important to “be sure that if it came to a confrontation that we would be the boss” and that the unit had been given “permission to shoot.”

The Turkish minister was eventually escorted out of the Netherlands in the early hours of Sunday.

Earlier, the Dutch also had refused Turkey’s foreign minister permission to visit. Both ministers wanted to address rallies about next month’s constitutional reform referendum on giving President Recep Tayyip Erdogan more power.

Dutch Prime Minister Mark Rutte repeated Tuesday – the last day of campaigning for Dutch elections that have been overshadowed by the diplomatic crisis – that Dutch authorities are working to de-escalate tensions with Ankara.