By Andrew Gray and Fatos Bytyci

TIRANA (Reuters) - The European Union is working on a new package of sanctions to increase pressure on Russian President Vladimir Putin over the war in Ukraine, EU Commission President Ursula von der Leyen said on Friday as leaders from across Europe met in Tirana.

The EU, however, has already adopted 17 sanction packages - the latest one this week - and diplomats say it is increasingly difficult to get the necessary unanimity among the bloc's 27 members to pass new measures.

"He does not want peace, so we have to increase the pressure, and this is why we are working on a new package of sanctions," von der Leyen said, referring to Putin, before the European Political Community summit in Albania.

"This package will include for instance sanctions on Nord Stream 1 and Nord Stream 2. It will include working on listing more vessels of the Russian shadow fleet and also lowering the oil price cap, and also more sanctions on the financial sector in Russia."

Nord Stream 1 and Nord Stream 2, each consisting of two pipes, were built by Russia's state-controlled Gazprom to pump natural gas to Germany under the Baltic Sea. They were ruptured by a series of blasts in 2022.

"Massive" sanctions European leaders have threatened over the past days would need U.S. support to succeed, officials and diplomats have said.

Meanwhile, Russian and Ukrainian negotiators were in Istanbul on Friday for what was billed as their first direct peace talks in more than three years, under pressure from U.S. President Donald Trump to end Europe's deadliest conflict since World War Two.

Putin on Sunday proposed direct talks with Ukraine in Turkey, but has spurned a challenge from Ukrainian President Volodymyr Zelenskiy to meet him in person, and instead has sent a team of mid-ranking officials to the talks.

NATO Secretary General Mark Rutte said Putin "made a mistake by sending a low-level delegation".

"What we saw yesterday and overnight is yet more evidence that Putin is not serious about peace," British Prime Minister Keir Starmer said as he arrived at the Tirana summit.

"He's been dragging his heels, and I think it's really important therefore, that we have absolute unity with our allies. We'll be working on that again today to be clear that there must be a ceasefire, but also to be clear that should there not be a ceasefire, then we will act together in relation to sanctions."

(Reporting by Andrew Gray and Fatos Bytyci in Tirana; Additional reporting by Benoit Van Overstraeten, Ingrid Melander, Bart Meijer, William James and Julia Payne; Writing by Ingrid Melander; Editing by Alex Richardson)