Media lawyer Julian Pike has defended advising News International to place the lawyers of phone-hacking victims under surveillance.
He told the Home Affairs select committee yesterday that the practice was 'justifiable'and he would 'do it again tomorrow".
Pike, head of media at Farrer & Co, had previously admitted advising the News of the World to carry out surveillance on lawyers Charlotte Harris and Mark Lewis, who between them have represented dozens of phone-hacking victims.
The Leveson Inquiry heard last year that the News of the World commissioned private investigator Derek Webb to spy on the pair to find out if they were having an affair and to see if they were breaking confidentiality agreements and sharing information about phone-hacking cases.
Pike insisted yesterday he had never instructed private investigators carry out illegal activity, but said they were sometimes used to trace witnesses or carry out background checks.
Commenting on the Harris and Lewis case, he said: 'I gave advice to News Group that some surveillance should be carried out in relation to both Mr Lewis and Ms Harris.
'That actual investigation and surveillance was carried out by somebody who the News of the World chose to instruct – I had no direct dealings with them at all.
'I instructed one particular agency to do one particular job, which was to look at some public and open documents.
'News of the World used an agent who I had no knowledge of whatsoever to carry out the surveillance, which is where I think it went wrong."
Commenting on the general use of private investigators, he added: 'It's very unusual and I've certainly not had cause to do it before and I hope I don't have the cause to do it again.
'But in these particular circumstances there was justification for doing it and I would frankly do it again tomorrow if I had the same circumstances."
He claimed there were 'serious concerns about breaches of confidentiality'by Lewis and Harris.