According to the newswire, the Socialist Party figurehead informed the head of the lower house she would be standing down at the end of the year.

Calmy-Rey is expected to speak to reporters on Wednesday afternoon after the weekly government meeting.

Switzerland's presidency is elected annually by a joint session of parliament, but usually rotates in turn among the seven members of the Federal Council or government. It is a largely honorific position with little powers.

The departure of Calmy-Rey, who has been in government since 2003, is seen as part of a Socialist Party strategy ahead of the October 23 parliamentary elections.

The elections are expected to be hard fought between the Socialists and the right-wing Swiss People's Party, currently the biggest group in parliament and expected to win more seats.

Copyright AFP (Agence France-Presse), 2011