COPENHAGEN (REUTERS) - A Russian warship early on Friday (June 17) twice violated Danish territorial waters north of the Baltic Sea island of Bornholm where a democracy festival attended by senior officials and business people was taking place, the Danish Armed Forces said.

Denmark called the action an unacceptable provocation.

The Russian embassy in Copenhagen said the Danes provided no evidence.

The Russian warship entered Danish waters without authorisation at 0030 GMT on Friday (8.30am Singapore time) and again a few hours later, the armed forces said in a statement.

The warship left after the Danish navy established radio contact, it said.

"A deeply irresponsible, gross and completely unacceptable Russian provocation in the middle of #fmdk," Denmark's Foreign Minister Jeppe Kofod said on Twitter, referring to the Democracy Festival of Denmark.

The annual festival is attended by senior government officials, including Kofod and Prime Minister Mette Frederiksen.

"Bullying methods do not work against Denmark," Kofod said.

He said the Russian ambassador had been summoned, which was confirmed by the Russian embassy in Copenhagen.

The ambassador was told that a Russian warship had "allegedly entered into the territorial sea of Denmark," the embassy said in a statement.

"No evidence of what happened, including the coordinates of the alleged crossing of the Danish maritime border by the ship, was presented," the statement said.

There had been no immediate threat against the festival or Bornholm, Danish defence minister Morten Bodskov told local media.

"We must accept that the Baltic Sea is becoming a high-tension area," Bodskov said.

Ukraine's defence minister said last month that Ukraine had started receiving Harpoon missiles from Denmark, deliveries that he said were the result of cooperation between several countries.

Western allies are supplying Ukraine with weapons to defend against Russian forces who invaded in late February.

On Friday, Ukraine said its forces hit a Russian naval tugboat with two Harpoon missiles in the Black Sea, the first time it has claimed to have struck a Russian vessel with Western-supplied anti-ship weapons.