The chief executive of Kraft Foods has not ruled out further Cadbury plant closures beyond the two years the firm is already committed to.
Irene Rosenfeld said she was unable to offer further commitments after a visit to Birmingham's Bournville factory.
But she said it would remain "the heart and soul" of its chocolate business.
Ms Rosenfeld said she regretted uncertainty caused by statements over the Somerdale plant near Bristol, the closure of which was confirmed.
The US firm sealed its takeover of Cadbury earlier this year after shareholders in the UK chocolate maker voted in favour of the deal.
Asked on Friday what she was expecting with the merging of the companies, a net loss or gain in jobs, Ms Rosenfeld said: "I think it's hard to say. It will vary area to area."
Speaking in March, Marc Firestone, Kraft executive vice-president, said: "We can commit that for a period of at least two years there will be no further closures of manufacturing facilities in the United Kingdom."
On Friday Ms Rosenfeld was asked if she was able to give "any more solid commitment to the future" of Bournville and the other plants in the West Midlands.
She replied: "We certainly understand that Bournville will remain at the, the heart and soul of our chocolate business and we are delighted about that.
"I think the key for us, though, this is a global business. We need to ensure that we are competitive on a global basis.
"As we bring together the combined company and we can share best practices. I think we have the opportunity then to take the business to a new place."
When it was suggested she was not able to make more of a commitment than at least two years, she said: "That's correct."
'Respect for employees'
In February Kraft said it planned to close the company's Somerdale factory in Keynsham, near Bristol, after previously saying it would keep it open.
Cadbury had earmarked the plant for closure, but Kraft's takeover had raised hopes of a reprieve.
On Friday Ms Rosenfeld said: "The comments that I made on Somerdale at the time were based on the knowledge that I had.
"I expressed a belief that we would be able to keep the facility open.
"I certainly regret the uncertainty that we caused as a consequence of some of our initial statements, but I think what's most important is that we are moving forward now.
"I believe we continue to treat the employees in Somerdale, as we do in all of our locations around the world, with respect."
Ms Rosenfeld came second in Forbes magazine's annual rankings of the world's most powerful women, beaten only by US first lady Michelle Obama.