BURY could swallow up two-thirds of Rossendale in a massive boundary shake-up following the election of a regional assembly.

The valley's borough council looks set to disappear if North West residents vote next year for an elected assembly. This would mean abolishing a tier of government, such as county and district councils.

Leaders at Bury Council, with their counterparts in Rochdale, have had early talks about picking up the pieces should the region vote "Yes".

Bury has looked at two options: a smaller one, where Bury would take in Edenfield, Stubbins and Helmshore. This would leave the main Rossendale towns to possibly form a new East Lancashire unitary authority, linking up with either Burnley or Hyndburn.

But Bury prefers the second, much larger option, which would see the borough adopt Rawtenstall, Haslingden, Helmshore, Stubbins, Edenfield and Waterfoot. The remainder of Rossendale, including Bacup and Whitworth, could transfer to an enlarged Rochdale borough. Under this plan, Bury's population would rise by a quarter, up 44,000 to 225,000.

Mr Mark Sanders, Bury Council's chief executive, said changes all depended on whether Rossendale would be abolished, but it was sensible for the council to make preparations.

"We are not into annexing people against their wishes," he said. "If Rossendale people see more of an identity with Burnley rather than Bury, good luck to them. In the meantime, we have to make sure it makes financial sense from Bury's point of view."

A merger would see Bury, rather than Lancashire, providing education and social services to Rossendale. They would also come under Greater Manchester for services such as the police, fire service, waste disposal and health.

Council leader John Byrne said: "We don't know what the outcome will be. It's obvious that there could be changes, but you can't just wait until the announcement is made. We are a neighbour of Rossendale, and need to know how changes would affect Bury and how the boroughs would fit together. It wouldn't be a takeover but an agreed merger."

Bury has to let the Boundary Committee know its views by September 8.