Neither Mr McCully nor Mr Allen were available for comment yesterday, but a spokeswoman said the ministry was "currently going through a significant change process to ensure it can deliver modern and high-quality services".
"It is too soon to talk about impacts on staff numbers at this stage, as we are entering into consultation with staff."
Public Service Association national secretary Brenda Pilott said the PSA was concerned that various changes proposed under the restructuring which had been under discussion for some time would affect the ministry's ability to represent New Zealand around the world.
"They have been looking at our various overseas posts as part of this review and it would be a concern to all of us if there was to be a reduction in our presence in key markets overseas."
Mr McCully said last year he had given an unambiguous message to Mr Allen that the ministry was in need of modernisation and rebalancing of resources "between the back office and the front line".
"This will mean significant economies in back office services in Wellington, and the elimination of many seconded administrative positions in overseas posts."
He indicated the ministry's focus would shift from Europe to Asia, the Gulf States, South America and Africa and "where we do not need to have missions, we will close them".