It said it would be clearer about who funded ads and to what end, especially those pushing a political agenda.

The company, like several tech firms, is keen to show it can self-regulate after it was found that Russian-backed groups were exploiting its ad platform.

Several key senators, from both sides of the US political divide, have backed measures clamping down on online ads.

The Honest Ads Act would regulate ad sales on social networks, search engines, websites or apps that have more than 50 million US visitors each month for the majority of months in a year.

The rules would bring it closer in line with restrictions and disclosures required when placing political messages on TV or radio stations.

'Good first step'

Twitter hopes its own measures, announced on Tuesday, will be at least partly enough to convince senators it is capable of tackling the problem itself.

Senator Mark Warner described the changes as “a good first step”, adding: “Online political ads need more transparency and disclosure.”

Twitter’s new measures include:

• An Advertising Transparency Center that will allow users to view what advertising campaigns are currently active on the site
• A special label for ads funded by political campaigns, including details on who the ad was targeted at
• Unspecified penalties for marketing firms that push political ads without being transparent about their origin
• More shared information about how long an ad campaign has been running

A blog post outlining the changes added: "People can also report inappropriate ads or give negative feedback (i.e. “I don’t like this ad”) for every ad running on Twitter, whether the ad targets you or not.

"This feedback will help us more quickly remove inappropriate ads from Twitter, and show you more relevant ads in your timeline.”

From Russia with tweets

Twitter, Facebook and Google face a Senate hearing next week in which they will be expected to describe and explain the extent in which Kremlin-backed accounts abused the sites’ advertising platforms.

At a hearing held last month, Twitter was criticised for not doing enough research into the matter. Senator Warner, who sits on the committee investigating Russian interference in last year’s presidential election, said Twitter’s appearance was “deeply disappointing”, and consistently mainly of information already divulged by Facebook.

That information included details about more than 400 Facebook profiles that the company found were likely being run by so-called “trolling farms” in Russia.

These farms would employ people to trawl the internet to post inflammatory comments - often focusing on a particular issue, like race or immigration, rather than a specific candidate.

Analysis of the activity has suggested the efforts were targeted at US swing states, i.e. areas where the election race is tight.

Google has said it discovered a small amount of ad buy - $4,700 - linked to Russian government groups. However, that does not include advertising and accounts on YouTube, something Google is still investigating, it said.