U.S. tech giants such as Apple, Google and Facebook will remain under close scrutiny by the EU's antitrust czar during her second term, according to a senior Brussels lawyer.

Andreas von Bonin, a partner with Freshfields Bruckhaus Deringer in Brussels and head of the firm's antitrust, competition and trade practice, said Margrethe Vestager, the EU's head of antitrust who was nominated for a second five-year term this week, would likely keep U.S. tech companies "under very close scrutiny."

During the last five years, Vestager, as the EU's main antitrust enforcer, took on most of the biggest U.S. tech companies in a number of cases. She hit Apple with a €14 billion (about $15.5 billion) bill for unpaid taxes, fined Google €1.49 billion ($1.7 billion) for abuse in the online advertising market, and charged Facebook €110 million ($122 million) for misleading competition authorities over the acquisition of messaging service WhatsApp.

Vestager's dogged pursuit of multinationals over tax issues caught the attention of President Donald Trump. In 2018, he said in reference to Vestager, "Your tax lady, she really hates the U.S."

But Vestager rejects accusations that she is singling out U.S. companies, pointing out that she has pursued Italian carmaker Fiat and other European companies for avoiding taxes.

In addition to nominating Vestager for a second term as competition commissioner, incoming EU President Ursula von der Leyen expanded her role to include oversight of digital issues. Her official title is executive vice-president for making Europe "fit for a digital age."

Von Bonin said von der Leyen's decision to keep Vestager as antitrust chief was a "resounding endorsement by European leaders of the way she has led competition enforcement over the last five years."

Vestager is also valued for her communication skills, von Bonin said, adding, "She was perceived as someone able to explain the benefits of competition enforcement for Europe and present it as a means of getting a 'fair deal' for citizens and consumers."

It is unclear how Vestager will combine her roles as antitrust enforcer and digital policy czar responsible for encouraging the EU's development in the digital field. "[This] is a new combination, von Bonin said. "We will need to see how this works in the coming years."