Russian President Vladimir Putin has accused the United States of pushing Western observers into boycotting Russian elections.
President Vladimir Putin said the US was trying to discredit the poll
Mr Putin said the goal was to discredit the parliamentary election to be held on 2 December.
The Organization for Security and Co-operation in Europe (OSCE) has categorically rejected the allegations.
Meanwhile, the European Commission has expressed concern at the treatment of the opposition in Russia.
The OSCE's election monitoring unit announced earlier this month that it would not attend Russia's election, saying Moscow had refused to provide visas to its staff.
The OSCE later said it would send a delegation of European MPs - rather than a full OSCE team - to monitor the vote.
Mr Putin said the boycott decision "was taken on the recommendation of the American state department".
"The aim is to discredit the elections, but they won't achieve their goal," he said.
"We will certainly take this into account with our bilateral ties with this state," he added, referring to the US.
But a spokeswoman for the OSCE in Warsaw, Urdur Gunnarsdottir, called Mr Putin's allegations "nonsense".
"The decision was not made in consultation with any government. It was made on operational, not political grounds," Ms Gunnarsdottir told the BBC.
"Our decision did not have the aim to influence the election."
The OSCE unites 56 member countries from Europe, Central Asia, the US and Canada.
The organisation will be represented by the OSCE Parliamentary Assembly, which, together with the Council of Europe Parliamentary Assembly, is sending about 100 MPs from member countries to Russia to observe the 2 December parliamentary poll.
The head of the European Union's executive arm, European Commission President Jose Manuel Barroso, has expressed worries about a weekend crackdown by Russian police on protests by opponents of President Vladimir Putin.
"I was very concerned to see reports of police harassment and arrests of politicians and peaceful demonstrators in Russia in the last two days," Mr Barroso said in a statement.
"The right to free speech and assembly are basic fundamental human rights and I very much regret that the authorities found it necessary to take such heavy-handed action."
Police broke up an opposition rally on Sunday, arresting 150 people in St Petersburg, including opposition leader Boris Nemtsov - who was later freed.
Another opposition figure, former chess champion Garry Kasparov, was arrested at a rally in Moscow on Saturday.