WASHINGTON, May 11 (Reuters) - Ukrainian President Volodymyr Zelenskiy on Thursday said he had approved a plan to reform criminal and law enforcement systems, a key element in plans to secure quick membership of the European Union.

Ukraine, fighting to repulse Russia's invasion, has formally applied for membership of the 27-nation bloc.

The EU sees an end to endemic corruption, upgrades to legislation and improvements to the judiciary as key elements in anchoring Ukraine in Western institutions.

"We must provide for a system that guarantees justice and rule of law in our country, compatible with our aim of quickly joining the EU," Zelenskiy said in his nightly video address.

The changes, he said, would be part of a new social contract ensuring people felt safe and protected.

"Trust in the state is grounded in trust in those who act in the name of the state. Law enforcement and the prosecution system are the keys to this, along with everyone who works in the state apparatus," he said.

Membership applications for the EU normally take years to process in order to complete the complicated process of bringing a candidate nation's laws and regulations into line with rules enforced by the bloc.

But Zelenskiy wants the process to be speeded up, with negotiations on membership to start this year. He said work on the basis of the new document would extend through 2027.

Zelenskiy's administration has already altered legislation and introduced measures to underpin key institutions as part of moves to secure financing from institutions like the International Monetary Fund.