LONDON - British Airways faces a strike ballot among cabin crew over proposed changes to working practices, just days after it announced a merger deal with Spanish carrier Iberia.

Trade union Unite said on Monday it was issuing ballot papers to its 12,000-plus members of BA's 14,000-strong cabin crew workforce.

We ask British Airways to signal that they are willing to abandon their plans to impose change and work with us on a way forward, one which delivers for passengers, shareholders and the workforce, Brian Boyd, Unite national officer for aviation, said in a statement.

The ballot will close on Dec. 14.

BA and Iberia agreed on Thursday to create a group with a combined market value of $7 billion as they try to battle the worst industry downturn in decades.

BA's pension deficit was a big stumbling block during 16 months of talks and Iberia has reserved the right to back out of the deal if the agreed funding hole turns out to be bigger than expected. Analysts have forecast a deficit of around 3 billion pounds ($5 billion). ($1=0.6017 pounds) (Reporting by Mark Potter; Editing by Greg Mahlich)