The editor of the Daily Mirror has conceded that phone hacking may have occurred at the newspaper.

Richard Wallace, who has edited the tabloid since 2004, told the Leveson Inquiry into press standards that voicemail interception might have taken place in the newsroom without his knowledge.

But he insisted that there are "significant positives" in tabloid journalism and said he was confident that reporters who worked at the newspaper acted within the code of practice.

Counsel to the inquiry David Barr asked Mr Wallace if he knew about hacking at the paper.

"Not to my knowledge," replied Mr Wallace.

Mr Barr asked if it might have occurred without his knowledge.

"It might well have," said Mr Wallace.

The press standards inquiry will hear from two other Trinity Mirror editors: the Sunday Mirror's Tina Weaver and Lloyd Embley of the People.

Further testimony will come from Sly Bailey, chief executive of Trinity Mirror, which also publishes two Scottish national titles and more than 160 regional newspapers.

The inquiry will receive evidence on Tuesday from Private Eye editor Ian Hislop as well as Guardian editor Alan Rusbridger, Times editor James Harding and Sunday Times editor John Witherow.