German prosecutors have filed charges against a Ukrainian national over the blowing up of the Nord Stream pipelines under the Baltic Sea in 2022.

The suspect, named only as Serhii K under German privacy laws, is alleged to have led and co-ordinated the attack on the pipelines that transported natural gas from Russia to Germany, German media reports say.

They say he is the same person arrested in Italy last summer and extradited to Germany in November. He has denied involvement.

No-one has admitted carrying out the attack, and Ukraine has denied involvement in the case which may have serious implications for its relationship with Germany.

Berlin law firm Menaker, which represents the Ukrainian man, told Reuters news agency that an indictment had been served on Wednesday. It gave no details of the charges.

Federal prosecutors confirmed for another news agency, AFP, that a man had been charged over the explosion.

According to German public broadcaster DW, which cited German media reports, the suspect is accused of leading a team of seven accomplices in an operation to destroy three of the four Nord Stream gas pipelines.

He is also accused of attacking civil energy infrastructure, as well as causing an explosion and destroying infrastructure.

The attack released record-breaking amounts of methane into the Baltic Sea and left the multi-billion dollar infrastructure inoperable.

A month after his arrest, a second Ukrainian suspect was detained at his home close to Poland's capital Warsaw on another arrest warrant issued by Germany.

Although Nord Stream 2 never went into operation, Nord Stream 1's two pipelines had provided a steady supply, along a 1,200km (745-mile) stretch of the Baltic Sea, from the Russian coast to north-eastern Germany.

Shortly before Russia's invasion of Ukraine in February 2022, Germany cancelled its process to approve Nord Stream 2, which was 100% owned by Russian gas giant Gazprom. Months later, Russia shut down Nord Stream 1, blaming problems with equipment.

Then, on 26 September 2022, several explosions were recorded that ruptured three of the four pipelines.

Mystery surrounded the identity of the saboteurs, with Russia itself coming under Western suspicion, and Moscow blaming the US and UK.

There is no evidence so far linking any state to the attacks.

Many Ukrainians consider whoever destroyed Nord Stream to be heroes for taking out an important revenue source for Russia, and struggle to understand why Germany – a key ally of Ukraine – is pursuing this prosecution.

Germany is Ukraine's biggest source of European military aid.