The Electoral Commission has backed away from the introduction of a specific code of practice in relation to non-broadcast political advertising.

In a report published on Monday, the commission concluded that it would be impractical to introduce a new code.

Only the Liberal Democrats and Plaid Cymru had indicated that they would abide by such a code, said the report.

Instead, it recommends that political advertisers abide by the principle enshrined in the existing advertising code that adverts should be prepared with "a sense of responsibility to consumers and society".

Political advertising has been exempt from the British Code of Advertising, Sales Promotion and Direct Marketing since October 1999.

In 1998 the Committee on Standards in Public Life recommended that political parties adopt a code of their own, but nothing has been agreed.

The Electoral Commission said there were a number of barriers to establishing and enforcing a new Code.

• A statutory code on political advertising is unsustainable given the right to free speech enshrined under the Human Rights Act.
  
  
• To seek to control misleading and untruthful advertising would be inappropriate given the subjective nature of political claims. There is a stronger case in principle for a voluntary code to protect against offensive advertising, which might be in the public interest.
  
  
• Any code would require the support of political advertisers. Only the Liberal Democrats and Plaid Cymru have indicated their probable support.
  
  
• A system considering complaints is unlikely to deliver sufficiently prompt adjudications to be of any value.
  
  
• A requirement that advertising copy go through some form of pre-clearance is impractical.
  
  
• A sufficiently independent adjudicatory body would need to be appointed with significant resources to ensure enforcement of a code.

The Electoral Commission concluded that on the basis of these findings a new code would not be viable.

"For a code of practice to succeed, whether statutory or voluntary, it will require the support and co-operation of political advertisers as well as a robust and workable system to operate under," said Electoral Commissioner Glyn Mathias.

"We have found no compelling evidence that these aims are either practical or achievable and so are recommending that no code be introduced at present."