According to BBC, it says it has been given no reason for the order, but correspondents say the move is thought be fall-out from the operation that killed Osama Bin Laden.
Following the raid, a Pakistani doctor was arrested for working for the CIA.
Pakistani intelligence officials accuse Save the Children of involvement – the group denies the claims. Six of its staff in Pakistan are foreigners.
The charity, which has operations all over the world, has worked in Pakistan for more than 30 years. Correspondents say that it is not thought that the forthcoming expulsions will have any significant impact on its operations in the country in the short term.
A Save the Children spokesman in London told the BBC that the charity was seeking “clarification” from the Pakistani authorities in relation to the expulsions. The spokesman said it was not yet clear whether the agency would be allowed to send replacement expatriate staff.
The Pakistani government has so far not officially commented on the expulsions.