US telecoms operators T-Mobile and Sprint finally merged on Wednesday, the companies said, bringing an end to two years of negotiations as the pair aimed to create a giant capable of competing with the sector's leading players.

The combined firm will have more than 100 million customers, claiming the scale to compete with larger wireless rivals Verizon and AT&T.

"T-Mobile US Inc. announced today that it has officially completed its merger with Sprint Corporation to create the New T-Mobile... that will deliver a transformative 5G network," T-Mobile and Sprint said in a statement published on both their websites.

They said the combined company will operate under the name T-Mobile.

New York, California and other states had attempted to block the tie-up on antitrust grounds, but a court decision in February paved the way for the third- and fourth-largest mobile carriers to complete their merger.

The final amount of the transaction was not released, but T-Mobile -- a subsidiary of Deutsche Telekom -- proposed $26 billion in April 2018 to buy Sprint, which is controlled by Japanese giant SoftBank.

The merger of Sprint and T-Mobile will create the third-largest wireless carrier in the United States
The merger of Sprint and T-Mobile will create the third-largest wireless carrier in the United States AFP / Alastair Pike

Backers of the deal argued that combining T-Mobile and Sprint would create a strong number three US wireless carrier behind Verizon and AT&T, with the resources to invest in 5G, or fifth-generation, networks.

Critics contended it would leave consumers with fewer choices and lead to higher prices.

T-Mobile said the merger would allow for a planned investment of $40 billion into its "network, business and more" over the next three years and "at least $43 billion" in value would be unlocked for shareholders.

T-Mobile president Mike Sievert said: "During this extraordinary time, it has become abundantly clear how vital a strong and reliable network is to the world we live in.

"The New T-Mobile's commitment to delivering a transformative broad and deep nationwide 5G network is more important and more needed than ever and what we are building is mission-critical for consumers."

The new company has promised to provide 5G to 99 percent of the US population within six years.

T-Mobile and Sprint stocks rose 1.47 and 2.13 percent respectively following the announcement.