Russia ran an information warfare campaign to disrupt the 2016 US presidential election, but there is no evidence that Donald Trump's campaign colluded with Moscow, Republicans on a congressional panel say in a new report.
The findings of majority Republicans on the US House of Representatives Intelligence Committee were immediately challenged by minority Democrats.
Republicans, over Democratic objections, voted in March to end the committee's investigation of election meddling.
The 253-page report was seized on by Trump, who posted its conclusions on Twitter and repeated his view that the Russian investigation is "A total Witch Hunt! MUST END NOW!" despite probes by a US special counsel and other congressional committees that are still open.
Trump has repeatedly denied receiving help from Moscow for his election campaign. The Kremlin denies meddling in the election.
The heavily redacted Republican report contains little new information about Russia's election interference or the Trump teams contacts with Russia.
But it criticises an array of actors for their response to the election meddling.
Then US President Barack Obama's response to Russia's actions was insufficient, it said, while the FBI's notification to hacking victims was "inadequate".
The report said that the Trump campaign should not have held a June 2016 meeting at Trump Tower with Russians who claimed to have damaging information about Democratic candidate Hillary Clinton, nor praised and communicated with WikiLeaks, which released documents hacked by Russia.
The interaction with WikiLeaks was "highly objectionable and inconsistent with US national security interests", it said.
Separately, a Russian lawyer who attended the Trump Tower meeting, Natalia Veselnitskaya, said in an interview with NBC News that she had Russian government ties.
"I am a lawyer, and I am an informant," she said.
Russia for years has conducted information warfare in Europe, running cyber operations, supporting fringe political parties and targeting disaffected populations to sow discord, the House committee said.
In the US election campaign, the report says Twitter identified 36,746 automated accounts and 2752 human-operated accounts linked to the Russian effort.
Russian operatives used paid advertising on Facebook to reach five million Americans, it said.
Democrats on the House Intelligence Committee released their own 98-page report, which charged that the Republican document "reflects a lack of seriousness and interest in pursuing the truth".
The panel's top Democrat, Adam Schiff, said they would continue their own investigation and this week "received new documents from another important witness".
The Senate Intelligence Committee is conducting its own investigation of Russia and the 2016 election.
Asked what the Senate panel had found regarding collusion between the Trump campaign and Russia, Democrat Senator Mark Warner said: "Stay tuned."