Twitter identified only 22 accounts on its platform that were directly tied to the Russian Facebook pages and then discovered another 179 accounts that were ârelated or linkedâ to the Facebook accounts. None were registered on the site as advertisers, the company said.
Twitter did not immediately respond to Mr. Warnerâs criticism.
Representative Adam B. Schiff of California, the top Democrat on the House Intelligence Committee, was more diplomatic about Twitterâs briefing for House investigators, calling it âgood, but preliminary.â
âI think there is a great deal more that we need to know, a great deal more that Twitter needs to find out,â he said. Mr. Schiff said Twitter faced greater difficulty in tracing accounts because its users provide less information than Facebook users when they sign up.
âAt the same time, I donât think we have more than scratched the surface of our understanding of how the Russians may have used that platform,â he said.
Senator Richard Burr of North Carolina, the Senate Intelligence Committeeâs Republican chairman, would not answer questions about the briefing on Thursday, and his spokeswoman declined to comment. Mr. Warner said that he and Mr. Burr would hold a news conference as soon as next week to update the public on their investigation and try to draw attention to the continuing threat by foreign entities to the American political system.
The cybersecurity company FireEye found hundreds of automated accounts linked to Russian hacking groups, which sent out messages critical of Hillary Clinton and the Democrats last year.
Nor did Twitter address a web âdashboardâ set up last month by researchers to track and compile statistics on 600 Twitter accounts that the researchers believe to be linked to the Russian government or to have a longstanding pattern of repeating its propaganda. The companyâs statement said nothing about still-functioning Twitter accounts of DCLeaks and Guccifer 2.0, which American intelligence officials identified last year as created by Russian agents to distribute emails and documents obtained by hacking.
Mr. Warner said he was âmore than a bit surprised in light of all of the public interest in this subject over the last few weeks that anyone from the Twitter team would think that the presentation they made to Senate staff today even began to answer the kinds of questions that weâd asked.â
He said the company had much more work to do.
âThis raises at an even greater level the necessity that the American public has the ability to know when they are seeing a political ad, whoâs behind it â particularly if it is being sponsored by foreign agents,â he said.
In its briefings for congressional investigators and its public statement, Twitter did not identify any of the suspect accounts by name. The company said it had suspended accounts that violated its terms of service, suggesting that it had allowed some of the Russia-linked accounts to continue to function.
Clinton Watts, a former F.B.I. agent who has tracked suspected Russian activity on Twitter for several years, said the platform had proved especially vulnerable to abuse, in part because the company demands little information from users. Twitter was used for years by the Islamic State for propaganda and recruiting, though much of that activity has now been shut down.
âBad people can do what they want on this platform,â said Mr. Watts, a senior fellow at the Foreign Policy Research Institute in Philadelphia. âI think they have real problems trying to trace the Russian activity.â
Facebook briefed the two intelligence committees on Sept. 6 and revealed that it had connected 470 profiles and pages to a shadowy Russian company with Kremlin links called the Internet Research Agency. It said the pages had placed 3,000 ads on Facebook costing about $100,000. It found another $50,000 in ads that it believed might have a Russian source.
While some of the pages and ads praised Donald J. Trump and excoriated Mrs. Clinton, Facebook said that most of the material sought to exacerbate divisions over immigration, race, guns, gay rights and other incendiary issues. Members of the Congressional Black Caucus wrote a letter this week to Facebookâs chief executive, Mark Zuckerberg, asking the company to look more deeply into the Russian activity.
Congressional investigators want to know more about how the Russia-linked Facebook ads were targeted to specific geographic and demographic groups. Officials familiar with Facebookâs briefings for Congress confirmed a CNN report that Russia-linked Facebook ads promoting the Black Lives Matter movement were specifically targeted at residents of Baltimore and Ferguson, Mo., both of which had been roiled by protests in response to police violence against black men.
Mr. Warner said on Thursday that the committee was still waiting for Facebook to deliver a set of ads that it had identified. He said he expected the material to be delivered by early next week.
The Senate committee has asked Google officials to come for a private briefing in the coming weeks, according to a congressional aide who spoke on the condition of anonymity because the aide was not authorized to discuss the matter publicly. The committee has invited Facebook, Twitter and Google to testify on Nov. 1.
The House Intelligence Committee announced on Wednesday that it intended to hold its own public hearing with tech companies next month, but it has yet to announce a date.