A mystery campaigner has asked the Swiss to name their preferred capital, by mobile phone text.

Since the start of January, billboards have gone up around the country's major cities inviting people to choose between the present federal capital Berne, and Basel, Geneva or Zurich.

But it is unclear who is behind the campaign and what their motives are.

"It's a committee that wants to remain anonymous," said Christof Hotz, who is running the poster campaign for advertising agency APG Affichage.

Hotz declined to elaborate on whether the campaign favored a change. Under the Swiss system of government, citizens can call a national referendum to amend the constitution by collecting 100,000 signatures.

The campaign's Web site, www.neue-hauptstadt.ch -- shows the current state of play, with Basel leading the way on Friday with over half of votes. Voting closes January 14.

"It's a simple vote by SMS," Hotz said by telephone. "The results will be published on the Web site. Then we'll see what happens."

Reuters