U.S. President Barack Obama waves as he boards Air Force One for departure at Tegel Airport in Berlin, capital of Germany, on Nov. 18, 2016. U.S. President Barack Obama left Berlin on Friday, ending his last visit to Germany and Europe during his term of office. (Xinhua/Shan Yuqi)

BERLIN, Nov. 18 (Xinhua) -- U.S. President Barack Obama on Friday ended his final presidential visit to Europe with a six-party talk here with German Chancellor Angela Merkel and the heads of government from France, Italy, Spain and Britain over key issues of foreign policy such as combating "Islamic state" (IS) and sanctions against Russia.

ABIDING BY RUSSIA SANCTIONS

The United States and five leading EU countries expressed their support for a continuation of the sanctions against Russia for the Ukraine conflict, the Obama administration announced on Friday after the six-party talks.

All the heads of state agreed that the penalties should remain in force as long as Russia does not fulfill its obligations arising from the Minsk armistice agreement, said the statement published by the White House.

The fact that no permanent ceasefire was adhered to is worrying, said the statement, adding that security must be guaranteed and free and fair elections must be held in the occupied areas of Donetsk and Luhansk.

On Thursday, Obama advised his successor Donald Trump to stand up to Russia if it strayed from Western principles.

"I've sought a constructive relationship with Russia," said Obama, "My hope is that the president-elect coming in takes a similarly constructive approach, finding areas where we can cooperate with Russia where our values and interest align."

The U.S. president also said he hoped that Trump does not simply take a realpolitik approach in cutting deals and doing "whatever's convenient at the time."

COMMON VALUES

According to the statement of the White House, the participants of the meeting on Friday also made a commitment to cooperate with NATO in the future.

Meanwhile, according to Merkel, the leaders agreed that the humanitarian situation in the disputed eastern part of Aleppo should improve.

The situation in the IS-occupied cities of Rakka in Syria and Mosul in Iraq was also discussed during the six-party talk. Leaders said it was important to promote the stabilization of liberated areas at an early stage.

Obama noted it was important for the Transatlantic Trade and Investment Partnership (TTIP) negotiations to be maintained.

The German chancellor emphasized that she had always spoken out for a trade agreement between the EU and the United States, the two major trading areas of the world.

"I continue believing that the EU is one of the greatest achievements in the world," said the outgoing U.S. president on Thursday in Berlin. Britain's exit from the EU should be conducted as "smoothly and orderly and transparently" as possible, he added.

Relations with the United States are a basic pillar of German foreign policy, Merkel said in her joint press conference with Obama.

CLOSE COOPERATION

Merkel thanked Obama for the "excellent cooperation" and praised Obama as a reliable partner in difficult times. She also expressed her gratitude for a close, trusting and friendly cooperation for a period of eight years.

The chancellor said she looked forward to a close cooperation with Trump. "Of course, I will do everything possible to work well with the newly-elected president," Merkel said.

Obama also thanked Merkel for the German contribution in the fight against Islamic State and in the Syrian conflict.

Obama's last official meeting with his European partners also touched upon the refugee crisis.

The meeting marked Obama's farewell visit to Europe before the U.S. president leaves office in January 2017.