Vodafone Group has agreed an 18.4 billion euro ($21.8 billion) deal to buy cable TV company Liberty Global's operations in Germany, Czech Republic, Hungary and Romania.

Vodafone said adding Liberty's cable TV and broadband services to its mobile operations would create the first truly converged pan-European company able to take on former incumbents like Deutsche Telekom.

It said combining the companies' operations would generate cost savings of about 535 million euros a year before integration costs by the fifth year after the deal completes.

The two companies, which already have a joint venture in the Netherlands which is excluded from the deal, restarted talks in February about Vodafone buying Liberty's assets in the other continental European countries where they overlap.

The deal is likely to face a lengthy regulatory approval process, with rivals such as Deutsche arguing that it will give Vodafone too much control of the market. Both sides are targeting a completion by around the middle of 2019.

A break fee of 250 million euros will be payable to the British company, in certain circumstances, if the deal does not complete.