In a letter to Guardian News & Media staff, McCall said without taking action to reduce costs, GMG Regional Media's losses would soon become "completely unsustainable", which could lead to "the end of the business and its newspapers altogether".
Both McCall's letter and today's leader in The Guardian said the changes were not being made to "service the ongoing expansion of the Guardian" as suggested in the ad, taken out by the National Union of Journalists' regional chapels across Guardian Media Group.
The ad criticised planned cuts to GMG's regional newspapers in Surrey and Berkshire, and the North West. GMG was also criticised for what the NUJ claimed were "devastating staff cuts to service the ongoing expansion of the Guardian - which is losing many millions, but still paying executive bonuses".
Instead, McCall said the changes in Greater Manchester, Surrey and Berkshire were designed to protect its regional business, titles and the employment of the majority of its staff, by bringing the company towards break-even.
Judy Gordon, NUJ father of the chapel at the Manchester Evening News, said the ad was taken out to "embarrass The Guardian" and "show its readers how the management treats its work force". Gordon said the regional papers had "made millions of pounds [for GMG] over the decades", so there should be "a bit more loyalty shown" to the regional titles.
As part of the GMG proposals MEN Media said it was looking to make 39 editorial staff redundant from both its combined weekly titles and the MEN.
MEN Media staff were told today that all 35 volunteers for redundancy at the weekly titles have been accepted and no compulsory redundancies will be sought.
All 18 people who volunteered for redundancy at the MEN have had their requests accepted and there will be a further 21 compulsory redundancies, 14 of which are classified as editorial. Letters to staff whose jobs are at risk will be posted over night.