BRUSSELS (REUTERS) - The European Union will do its best to seal an agreement on new ties with Britain by the end of the year but will not compromise its core values to achieve that, the bloc's chief executive, Ursula von der Leyen, said on Wednesday (June 17).

The president of the European Commission told the European Parliament that British Prime Minister Boris Johnson confirmed to her that London would not seek to prolong negotiations beyond this year for a new EU-UK trade deal after Brexit.

"We're ready to be creative to find common ground," von der Leyen said. "It should be a shared interest for the European Union and the UK to never slide backwards and always advance together towards highest standards."

Britain left the EU, the world's largest trading bloc, on Jan 31 after 47 years of partnership to the huge regret of the bloc. But there has been little progress on designing a new relationship.

The EU says Britain cannot retain all the economic and trading benefits it had as an EU member, while London says Brussels is not showing enough flexibility in talks.

Von der Leyen said there could not be a deal without so-called level playing field guarantees of fair competition, an agreement on fisheries and on dispute-settling mechanisms.

She said Britain must offer solid legal guarantees that it would handle sensitive data of EU citizens correctly if it wanted access to the bloc's databases or close judicial and police cooperation.

"No one can say with certainty where these negotiations will be at the end of the year," she said.

"We are now halfway through these negotiations with five months left to go. But we're definitely not halfway through the work to reach an agreement with little time ahead of us. We will do all in our power to reach an agreement."