New files released by Facebook to a committee of MPs investigating the social network have revealed that the official Vote Leave campaign spent more than £2.7m on targeted ads during the 2016 Brexit referendum.

The ads, created by Canadian company AggregateIQ, were often focused on specific issues such as animal rights or the NHS, although many also honed in on immigration. The released files also show how Vote Leave and BeLeave, another campaign, broke electoral law by working together and sharing data.

A number of BeLeave ads were sent from the Vote Leave Facebook account, and Vote Leave also shared data from a competition it ran early on in the campaign. The contest, which like many of the ads, did not clearly mark itself as being from the Vote Leave campaign, offered contestants £50m if they could correctly guess the result of all 51 games in the 2016 European football championship.

The contest, which was described by one Vote Leave insider as a “game changer” in terms of data gathering, was estimated to have odds of one in 5,000,000,000,000,000,000,000.

The 120 pages of documents that have been released so far reveal 1,433 different messages that were sent from the campaigns, which were seen more than 169m times in total. The BeLeave messages were directed at younger voters, promising a brighter future if the UK could leave behind restrictive EU regulations, while Vote Leave messages tended to focus on how much money was being contributed to the EU by the UK, with 140 ads referencing the false claim that the £350m sent to the EU every week could be spent on the NHS instead.

In a letter to the committee, Facebook said it was unable to disclose ads run by AggregateIQ for another pro-Brexit campaign, Veterans for Britain, as the campaign “has not permitted us to disclose that information to you”, which suggests that this picture of the impact Facebook had on the Brexit campaign is not yet complete. AggregateIQ has also been linked to Cambridge Analytica, the political consultancy at the centre of Facebooks data misuse scandal, and is under investigation by Canadian data watchdogs.