McDonnell: Belfast to lose 'clout' along with fourth seat
The SDLP MP for South Belfast said Belfast will lose "status and clout" by being reduced to three parliamentary seats.
Alasdair McDonnell said that Belfast should retain four seats in order to maintain the importance of the capital.
But the proposed boundary changes will see the number of Westminister seats in Northern Ireland reduced from 18 to 16.
South Belfast will now be divided between the current East and West Belfast constituencies.
The West Tyrone seat will also disappear and current Sinn Fein MP for the constituency, Pat Doherty, said his party must look at the full details of the consultation.
Alliance East Belfast MP Naomi Long welcomed the new boundaries which she said could strengthen her hold on the seat she won from the DUP's Peter Robinson in 2010.
The DUP has not commented on the new boundary proposals, saying it wished to fully consider the proposals before making a response.
Dr McDonnell said cutting Belfast to just three seats at Westminster will reduce the city's "clout".
"I have worked in South Belfast for 30 years and built up a good record of service. To see the constituency shredded - there is no question it's gone," said the South Belfast MP.
"From a status, from an authority and from a clout in political terms Belfast is now a smaller place as a result of these boundary changes.
"In my opinion they should have followed the people of Belfast out to the boundaries. In other words Belfast should have expanded."
But where the SDLP feels it may lose out, the position of the Alliance Party could be strengthened.
"From our perspective, we feel that it's a good seat for Alliance," said Mrs Long.
"Some of the areas which would be coming back into East Belfast would be very good areas for us in the previous assembly elections and so on.
"They moved out of South Belfast just before the last Westminster elections.
"However, you are never complacent about these things. You have to go in, you have to justify your existence and that's what we would be intending to do, regardless of where the boundaries are drawn."
Outside of Belfast the biggest change is in Tyrone and the Sinn Fein MP for West Tyrone will see his seat go.
"We will have to examine all of this. The consultation period has been laid out and includes the public hearings and we will avail of all that," said Mr Doherty.
"All of this is going to take some looking at and studying.
"Having a big geographical area isn't a new thing. Whatever way it shapes out we will be able to cope with that."