Vodafone Group's (VOD) multi-billion-pound merger with Three is expected to be approved if the companies commit to investing in a large-scale upgrade of the UK's mobile network, the Competition and Markets Authority said Tuesday.

The watchdog said that short-term measures to protect customers should be put in place to prevent price increases and resolve competition concerns for the merger to go ahead.

The CMA provisionally found that a commitment to carry out a network investment program would "significantly improve" the quality of the merged company's mobile network and boost competition between mobile network operators.

"The merger is a once-in-a-generation opportunity to transform the UK's digital infrastructure - which lags significantly behind its European peers," the companies said in a joint statement.

Vodafone and Three are required to deliver their joint network plan, commit to retain certain existing mobile tariffs and data plans for at least three years, and commit to pre-agreed prices and contract terms.

The CMA's final decision on the merger is due by Dec. 7.

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