US tech companies will also have to show details of political advertising on their platforms.Amazon, Apple, Facebook and Alphabet unit Google may have to alter their business practices in Europe or face stiff fines between 6-10% under new draft European Union (EU) rules to be announced on Tuesday.The rules are the most stringent attempt by the 27-country bloc to rein in the US tech giants' power that control troves of data and online platforms on which thousands of companies and millions of Europeans rely on.They also mark the European Commission's frustration with its antitrust cases against the tech giants, notably Google, which critics say did not address the problem.Regulatory scrutiny has been growing worldwide of tech giants and their power.European Competition Commissioner Margrethe Vestager and EU Internal Market Commissioner Thierry Breton will present the rules, a bid not just to rein in tech giants but also to prevent the emergence of anti-competitive dominant companies.One group of rules called the Digital Markets Act calls for fines up to 10 per cent of annual turnover for online gatekeepers found breaching the new rules, a person familiar with the matter told Reuters.It also sets out a list of dos and don'ts for gatekeepers, which will be classified according to criteria such as number of users, revenues and the number of markets in which they are active, other sources said.The second set of rules known as the Digital Services Act also targets very large online platforms as those with more than 45 million users.