An antitrust lawsuit filed by 44 US states has alleged that 20 pharmaceutical companies that make generic drugs have collaborated to fix prices and reduce market competition.

The lawsuit accused Teva Pharmaceuticals, Novartis’ subsidiary Sandoz , Mylan and Pfizer among others. The action has been filed by Connecticut attorney general William Tong.

Furthermore, 15 individual senior executive defendants were accused of being responsible for sales, marketing, pricing and operations of these drugs.

With Teva alleged to be at the centre of the conspiracy, the drugmakers are claimed to have manipulated the prices of more than 100 different generic medicines that account for billions of dollars of sales in the US.

According to the complaint, the competitors allegedly plotted to artificially raise drug prices, which were increased more than 1,000% in some cases.

The drugs spanned across all types, including tablets, capsules, creams and ointments, and across a variety of conditions such as diabetes, cancer, epilepsy, multiple sclerosis and HIV.

“We have hard evidence that shows the generic drug industry perpetrated a multi-billion dollar fraud on the American people.”

An investigation in its early stages found that executives from the accused companies met at industry dinners, lunches, cocktail parties and golf outings.

The lawsuit claims that communication for the illegal agreements was carried out via telephone calls, emails and text messages.

Tong said: “We have hard evidence that shows the generic drug industry perpetrated a multi-billion dollar fraud on the American people.

“We have emails, text messages, telephone records, and former company insiders that we believe will prove a multi-year conspiracy to fix prices and divide market share for huge numbers of generic drugs.”

The states are seeking damages, civil penalties and actions to restore competition to the generic drug market in the country.

Teva denied the allegations and said that it would defend against the lawsuit, reported Reuters.

This lawsuit expands the original complaint that was made in 2016 at the US District Court in the Eastern District of Pennsylvania and now includes 18 corporate defendants, two individual defendants and 15 generic drugs.