The Advertising Standards Authority (ASA) has revealed that 19 complaints have been sent about the UKIP campaign, but that the case has been closed as the ads fall into the remit of political advertising.
Political advertising falls outside the ASA's jurisdiction, as it is deemed inappropriate for the body to intervene in the democratic process.
The ASA said: “We appreciate that political ads can and will prompt complaints. However, the best course of action for anyone with concerns about a political ad is to contact the party responsible and exercise your democratic right to tell them what you think.
“Despite this, we’ll nevertheless shortly be writing to all the major parties campaigning in the upcoming elections to encourage them to stick to the principles in the Codes, even if they’re not bound by them.”
The £1.5m UKIP campaign, which launched last week, includes 48-sheets, press and online adverts.