BRUSSELS (Reuters) - U.S. companies, including tech rivals Microsoft and Google, were among leading spenders on corporate lobbying in Brussels last year, a Reuters review of new data showed (table below).

A logo is pictured at Google's European Engineering Center in Zurich April16, 2015. REUTERS/Arnd Wiegmann

Companies had until Thursday to update public entries in the European Union’s newly revamped Transparency Register following a tightening of rules in January that obliges firms to register if they want to meet EU commissioners and senior staff.

Oil majors Exxon Mobil of the United States and Anglo-Dutch Shell shared the top spot with Microsoft, with reported spending in their last financial years of between 4.5 and 4.5 million euros ($5.0-5.6 million).

Those figures were broadly in line with the trio’s spending in previous filings recorded in January by researchers at anti-corruption group Transparency International -- the Commission itself does not provide comparative data with previous years.

However, some of the other big spenders recorded sharp increases, including Google and Germany’s Deutsche Bank, which doubled their expenditure, U.S. chemicals group Dow, which recorded four times the level of spending as its previous entry.

None of the companies listed offered comment.

Google, subject of a high-profile antitrust case launched by the Commission two weeks ago after a five-year investigation, spent 3.0-3.5 million euros ($3.4-3.9 million), the same as Dow. Microsoft, which has itself been fined heavily in the past by EU antitrust authorities, has been prominent among those pursuing complaints against its American rival Google.

Two German companies were among those which spent 3 million euros or more last year. Deutsche Bank was the fourth biggest spender, reporting lobbying activity worth 3.96 million euros, and engineer Siemens spent 3.23 million.

China’s tech leader Huawei Technologies [HWT.UL] reported spending of 3.0 million euros in 2014. That was the same as it had previously reported as spending in its 2012 fiscal year.

DATA QUALITY IMPROVING

Also reporting spending of 3.0 million was paij GmbH, a German company that sells a mobile payments app and which put itself on the Register for the first time in March. Officials at the company could not immediately be reached for comment.

U.S. engineering firm General Electric reported lobby spending in the EU of 3.25-3.50 million euros for 2013. No 2014 data appeared on its page on the Transparency Register.

Transparency International’s Daniel Freund said some changes in data filed appeared to reflect a recognition among companies that the Register now set more rigorous reporting requirements. Over 1,000 organizations registered for the first time after Jan. 27, when it became a condition for access to officials.

“The data quality seems to be getting better,” Freund said, while noting that the Register only went some way to clarifying how much effort was going in to lobbying in Brussels and saying that the Commission appeared to have so far put only limited staff resources into scrutiny of the accuracy of entries.

Other organizations, including non-governmental pressure groups, must also declare spending. Environmental lobby Greenpeace, for example, declared 1.0-1.25 million euros in 2013.

A second element of transparency introduced under European Commission President Jean-Claude Juncker since he took office in November is a register of contacts by commissioners and senior staff with companies, lobby groups and their representatives.

Transparency International research found U.S. firms Google, Microsoft and General Electric, as well as European planemaker Airbus, were among the most active in visiting top EU officials since such meetings first had to made public in December.