According to the research, the pharmaceutical sector increased sevenfold its lobbying push for TTIP from 2012-13 to 2013/14.

The financial and machinery sectors also significantly stepped up their game during the same period according to the research.

The study was also carried out by SumOfUs, a global consumer advocacy group.

Corporate Europe Observatory and SumOfUs said they had seen a "dramatic corporate bias" in the Commission’s approach to the trade deal with the big business leaning not changing significantly since Cecilia Malmström took over as EU Trade Commissioner in November 2014.

According to the research, in her first six months in office, the Commissioner, members of her Cabinet and the director general of DG Trade had 122 behind-closed-doors lobby meetings in which TTIP was discussed. 100 of these meetings were reportedly with business lobbyists – 22 with public interest groups.

The research also aims to shed light on how "agenda-setting" for TTIP has been "driven"by Western European and US businesses while companies from Greece, Portugal, Cyprus, Malta, and Eastern Europe are not lobbying at all.

Also, one in five corporate lobby groups meeting the Commission’s trade department on TTIP are allegedly absent from the EU’s Transparency Register, among them reportedly large companies such as Maersk, Levi's and AON as well as powerful federations such as the world’s largest biotech lobby group BIO and the Big Pharma lobby group PhRMA.

Pia Eberhardt, trade campaigner with Corporate Europe Observatory said: “This data justifies millions of citizens' concerns about the threats posed by TTIP. While big business lobbyists are kept firmly in the loop and exert a powerful influence over the negotiations, public interest groups are kept at bay.

"The result is an agenda for TTIP that calls into question key standards and rights for citizens and the environment while dramatically expanding business power over politics in both the EU and the US."

The study claims that in the early phases of the TTIP negotiations (January 2012 – February 2014), DG Trade had 597 behind-closed door meetings with lobbyists to discuss the negotiations.

Some 528 of those meetings (88%) were claimed to be with business lobbyists while only 53 (9%) were with public interest groups.

"So, for every meeting with a trade union or consumer group, there were 10 with companies and industry federations," says CEO.

It goes on, "This pattern hasn't changed significantly since the new Commission took office in November 2014. In the first six months of the job, Cecilia Malmström, members of her Cabinet and the director general of DG Trade had 122 one-on-one lobby meetings behind-closed doors in which TTIP was discussed. 100 of these meetings were with business lobbyists – but only 22 with public interest groups.

"So, for every meeting with a trade union or a consumer organisation, Malmström and her staff had 5 get-togethers with companies and their lobby groups."

CEO and SumOfUs also claim that the corporate lobby groups which "lobbied hardest" for TTIP in the early phases of the negotiations are: the European employers’ federation BusinessEurope, the Transatlantic Business Council (representing over 70 EU and US-based multinationals), the European car lobby ACEA, the chemical lobby CEFIC, the European Services Forum, the European pharmaceutical lobby EFPIA, Food and Drink Europe, the US Chamber of Commerce and Digital Europe (whose members include all the big IT names, like Apple, Blackberry, IBM, and Microsoft).

They said: "These business sectors have lobbied most for TTIP in the early phases of the negotiations: agribusiness and food, cross-sectoral lobby groups such as BusinessEurope, telecom & IT, pharmaceuticals, finance, engineering & machinery, automobiles, health technology, chemicals, express & logistics."

CEO and SumOfUs go on to claim that several sectors have "significantly stepped up" their lobbying for TTIP with the pharmaceutical sector increasing its lobbying for TTIP seven-fold.

"While only 2,4% of DG Trade’s one-on-one lobby meetings on TTIP were with Big Pharma in the early phases of the negotiations (January 2012 to March 2013), the sector’s share in lobby meetings jumped to 16,5% in the period after (April 2013 to February 2014). The engineering and machinery sector has tripled its TTIP lobbying effort in the same period (from 3,0% to 9,5% of the behind-closed-doors meetings with DG Trade). Financial sector lobbying also doubled (from an 5,1% share in the total amount of corporate lobby meetings on TTIP to 10,8%)."

They claim that, "One in every 5 corporate lobby groups which have lobbied DG Trade on TTIP are not registered in the EU’s Transparency Register, amongst them large companies such as Maersk, AON, and Levi’s.

"Industry associations such as biotechnology lobby BIO, pharmaceutical lobby group PhrMA and the American Chemical Council are also lobbying under the radar. More than one third of all US companies and associations which have lobbied DG Trade on TTIP are not in the EU register."