LONDON: British lawmakers slammed the government on Tuesday for failing to look into possible Russian meddling in UK politics, particularly the divisive 2016 Brexit referendum, as they released a long-awaited report into the issue.

The document by parliament's Intelligence and Security Committee (ISC) had been expected to shed light on possible Kremlin interference in the landmark vote that saw Britain leave the European Union.

But MPs said they were unable to come to any firm conclusions because the current government or its predecessor had not ordered any investigation, owing to an apparent "lack of curiosity".

"Nobody wanted to touch this issue with a 10-foot pole," said committee member Stewart Hosie of the Scottish National Party.

"This is in stark contrast to the US response to reports of interference in the 2016 US presidential election.

"No matter how politically awkward or potentially embarrassing, there should have been an assessment... and there must now be one, and the public must be told the results."

Foreign Secretary Dominic Raab rejected claims the government had "actively" sought not to delve deeper into the perceived threat of Russian interference.

"We've got a long period recognising the enduring, significant threat posed by Russia to the UK, including in cyber. Russia is a top national security priority," he said.

In a separate 20-page response, the government said there was "no evidence of successful interference in the EU referendum" and denied acting too slowly on the threat.

The ISC report, delayed for 15 months, was being closely watched because of the Brexit campaign and result, which has dominated British politics for the last four years.

Political deadlock and infighting were finally broken when Boris Johnson won a huge majority at elections in December, allowing him to force his Brexit deal through parliament.

Diplomatic ties between London and Moscow have been fraught since 2006 when President Vladimir Putin was blamed for the radiation poisoning of former KGB agent Alexander Litvinenko in the British capital.