Comcast Corp and Time Warner Cable have abandoned their proposed $45 billion merger after US regulators said the deal would give Comcast an unfair advantage in the internet-based services market.

The Department of Justice said the plan to merge the two biggest US cable companies would have made Comcast an "unavoidable gatekeeper" for broadband services.

The deal had faced vocal criticism from some politicians, media company executives and diverse consumer and industry groups, who had worried it would create a monolith with too much control over what Americans do online and watch on television.

Federal Communications Commission chairman Tom Wheeler said the merger would have posed an "unacceptable risk to competition and innovation".

The US cable TV industry has been rapidly consolidating in the past few years as it grapples with the rising popularity of satellite and web-based entrants such as Netflix.