Vladimir Putin
© EPA/ALEXEI DRUZHININ / SPUTNIK / KREMLIN POOL

Ukraine's Foreign Ministry once again sent a note of protest to the Russian Foreign Ministry on Friday in connection with a trip to Crimea by Russian President Vladimir Putin.

"The Ukrainian Foreign Ministry expresses strong protest over Russian president's stay in the Ukrainian territory on August 19 that was not coordinated [with the Ukrainian side]," the note said.

Putin arrived in Crimea on Friday for a session with permanent members of the Russian Security Council. It is his first trip to the peninsula after recent attempted terrorist attacks by Kiev.

Ukraine also complains to the UN.

Ukraine's permanent representative to the United Nations Vladimir Yelchenko on Friday met with UN Deputy Secretary General Jan Eliasson to discuss Russian President Vladimir Putin's visit to Crimea, the Ukrainian permanent mission said.

"Vladimir Yelchenko met with UN Deputy Secretary General Jan Eliasson. They discussed Vladimir Putin's illegal stay in Crimea. Yelchenko also drew Jan Eliasson's attention to concentration of Russian armaments along the Russian-Ukrainian border in Crimea and Donbass," the mission said on Twitter.

The Republic of Crimea and Sevastopol, a city with a special status on the Crimean Peninsula, where most residents are Russians, refused to recognize the legitimacy of authorities brought to power amid riots during a coup in Ukraine in February 2014.

Crimea and Sevastopol adopted declarations of independence on March 11, 2014. They held a referendum on March 16, 2014, in which 96.77% of Crimeans and 95.6% of Sevastopol voters chose to secede from Ukraine and join the Russian Federation. Russian President Vladimir Putin signed the reunification deals March 18, 2014.

Last week, Russia's Federal Security Service (FSB) said it had thwarted attempted terrorist attacks in Crimea plotted by Ukraine's Defense Ministry's main intelligence directorate. A group of saboteurs was spotted in the small hours of August 7 near the city of Armyansk, close to the border with Ukraine. Two Russian servicemen were killed in the process of detaining the terrorists. The aborted terror attempts were designed to target Crimea's critical infrastructure and vital facilities, the FSB said.

Russian President Vladimir Putin slammed the Ukrainian special services' attempted sabotage plot in Crimea as irrational and criminal. Ukrainian President Pyotr Poroshenko dismissed Moscow's accusations saying this was a provocation.