Senate Minority Leader Harry Reid has written a letter to FBI director James Comey urging him to investigate alleged Russian plans to alter US election results Reuters

US Senate minority leader Harry Reid has asked the FBI to investigate alleged Russian attempts to manipulate the voting results of November's presidential election.

In a letter to FBI director James Comey, Reid wrote that the threat of Russian interference in the election "is more extensive than is widely known and may include the intent to falsify official election results", the New York Times reported.

Recent classified intelligence briefings had left him concerned that Russian President Vladimir Putin's "goal is tampering with this election", Reid said in an interview with the publication.

On Monday (29 August), Yahoo News reported that the FBI warned state election officials that foreign hackers had stolen voter registration data in at least one state, and gained access to the systems of another.

Previously, concerns over foreign hackers prompted Homeland Security Secretary Jeh Johnson to convene a conference call with state officials, in which he offered his department's help to make state voting systems secure from infiltration.

Officials familiar with the case said the states whose systems were compromised were Arizona and Illinois, with Arizona taking its voting registration system offline between 28 June to 8 July to allow for alleged security compromises to be examined.

It comes after Russia was accused of hacking the computer system of the Democratic Party, and leaking information indicating that senior party officials favoured Hillary Clinton over her rival, Bernie Sanders, in the battle for the party's nomination as presidential candidate.

Concerns have also been raised over connections between senior officials advising Republican Presidential Candidate Donald Trump and Russia. In the letter, Reid called for the connections to be investigated.

Trump campaign chairman Paul Manafort recently quit, with controversy surrounding his alleged acceptance of millions of dollars to lobby on behalf of Ukraine's deposed pro-Russia President Viktor Yanukovych.