Top mobile telecoms gear maker Ericsson's decision to quit the modems business will mean around 1,000 staff will have to leave the company, its chief executive said on Thursday.

The business, which Ericsson took sole ownership of from joint venture partner STMicroelectronics a year ago, employs around 1,600, some of whom will be transferred to research and development within radio networks, Ericsson said.

"This of course means a large part of staff will have to leave Ericsson," Chief Executive Hans Vestberg told Reuters, adding roughly 1,000 people would have to leave, although it was too early to give an exact figure.

In total, Ericsson employed slightly more than 115,000 at the end of the second quarter.