February traditionally heralds a decrease in monthly traffic figures due to the shorter month, but the number of monthly visitors to Metro.co.uk rose to just over 27.5 million, a 19.9 per cent increase on February and an almost 350 per cent increase on February 2013.
Dominic Rowell executive director at Metro, said: "We are delighted with the performance, our traffic is up across the board, not least of all via social where our Facebook visitors were up 1,319% year-on-year in February and our mobile traffic is +554% year-on-year. This is testament to our focus on a social, mobile, viral model."
Visitors to the MailOnline fell by 12.5 per cent to 165.9 million, although that figure remains the highest among publications audited by ABC.
In March, the Daily Mail & General Trust (DMGT), which owns both Metro.co.uk and the MailOnline, announced the Metro website would be "integrated" into MailOnline with immediate effect, to combine the relative merits of the two sites.
The Independent saw the biggest month-on-month drop in its online traffic in February as the number of monthly visitors fell by 13 per cent to 29.8 million, followed by the Telegraph, which fell by 12.7 per cent to 59.7 million.
Standard.co.uk saw a small drop in visitors, of just under 5 per cent to 5.16 million.
Monthly traffic to The Guardian and the Mirror Group websites both increased slightly, by 0.8 per cent to 91.1 million, and 1.2 per cent to 41.14 million, respectively. Monthly unique browsers recorded for Mirror.co.uk showed a 146.1 per cent increase since February 2013 as Trinity Mirror continues to experiment and explore new digital offerings.
For the first time, Express Newspapers had traffic figures reported for their websites. Express.co.uk recorded 9.37 million visitors and DailyStar.co.uk had 5.8 million visitors in February.
Update: Malcolm Coles, general manager of Mirror.co.uk, said the growth in monthly traffic at the Mirror validated the trend of focussing on Trinity Mirror's digital output with experiments such as humour site UsVsTh3m, launched last May, and data site Ampp3d, launched in December, both of which have a focus on social sharing.
"The lessons we've learned around how to display content in a visually-interesting way and how to expose content to new audiences is paying off," Coles told Journalism.co.uk. "It's great journalism and stories that people want to read about overlaid with new strategies in delivering those stories digitally."
Coles also highlighted the first ABC report of group-wide monthly traffic figures for Trinity Mirror, including both the regional and national websites, to "give a proper judgement of the Trinity Mirror network".
The Trinity Mirror Group - Digital certificate – which includes figures from national sites for the Mirror, Irish Mirror and Daily Record alongside regional websites for the Manchester Evening News; the Liverpool Echo; The Surrey Advertiser; Wales Online; The Reading Post; The Birmingham Mail; The Chronicle; The Middlesborough Evening Gazette and The Huddersfield Daily Examiner – reports a combined monthly total of 59.53 million unique browsers.
Almost half of this total is made up of visits from mobile devices, at 27.63 million mobile unique browsers.
This article was also updated with a quote from Dominic Rowell, executive director at Metro.