Metro is said to be looking at increasing distribution on London buses and also at restocking bins at stations after indicating that many of these are empty by 9am.
Sources said the proposals to increase Metro's circulation are still at the discussion stage. There has been internal debate at the company surrounding Metro's impact on the sales of the Daily Mail.
An Associated spokesman said: "The plans are being discussed, nothing is confirmed."
Associated accused News International of being "totally irresponsible" in raising the- londonpaper's print run by 100,000. The publisher of the Evening Standard and London Lite said the hike in distribution, to more than 500,000 copies, was "meaningless, unless there is an increase in demand", and said that NI's actions could lead to an increased litter problem.
NI issued a strong response, pointing out its recent capture of the Network Rail distribution contract allowed it to distribute more than 100,000 copies of thelondonpaper at stations. Ian Clark, the general manager of thelondonpaper, said: "It's a desperate measure from Associated and to say we are irresponsible is laughable. What is irresponsible is to put out 400,000 copies of a spoiler that they [Associated] clearly don't believe in."
Associated's criticism follows the release of January's newspaper circulation figures, which show the NI title increasing its circulation by 6.9 per cent to 436,345. Distribution of London Lite was flat at 400,977. The sales of the Evening Standard fell 17.9 per cent year on year to 276,562.