There are now three European Uinion cases against Google in total, including the charges in April for its Android mobile phone operating system

EU anti-trust authorities have granted US tech giant Google a few extra weeks to answer charges that it has abused its market dominance, an EU official told AFP on Friday.

The Silicon Valley firm now has until October 13 to answer questions about its Google Shopping , October 26 for its Adsense advertising business and October 31 for its Android mobile phone operating system.

"In each of these cases, Google asked for additional time to review the documents in the case file," according to an official from the European Commission, the executive of the 28-nation union.

"In line with normal practice, the commission analysed the reasons for the request and granted an extension allowing Google to fully exercise its rights of defence," the official told AFP.

Brussels has accused Adsense of restricting some websites from displaying ads from Google's competitors.

The EU has also recently beefed up its charge sheet in an earlier case against Google which alleges that the firm abused the dominance of its search engine for online shopping.

There are now three EU cases against Google in total, with the EU having also filed charges in April against it for its Android mobile phone operating system.

Google has already offered a general defence against the charges from the European Commission.

Former Danish economy minister Margrethe Vestager has launched a series of EU anti-trust cases against US firms in the past two years, drawing complaints from Washington.

Other EU investigations include cases against Starbucks, Amazon and McDonald's.

Google's response will be the company's last chance to avoid sanctions, which could amount to fines up to 10 percent of the group's annual global sales or $7.4 billion based on their 2015 results.