DUBAI (Reuters) - Iranian authorities took two daughters of detained opposition leader Mirhossein Mousavi from their homes on Monday, releasing them after several hours of questioning, news agencies reported.

Mousavi - a figurehead of the "Green movement" that alleged that the last presidential election was rigged - has been under house arrest with his wife for two years and is effectively barred from any role in a new election due this June.

Zahra and Narges Mousavi were summoned to give "explanations" to prosecutors, the Iranian Students' News Agency (ISNA) quoted the judiciary spokesman's office as saying.

It did not specify what they were questioned about but it may be connected to a statement they issued last month complaining they had been denied access to their parents for weeks.

While some hardliners have called for Mousavi and fellow Green leader Mehdi Karoubi to be prosecuted and possibly executed for their role in the 2009 protests, authorities have chosen to silence them instead by confining them to their homes.

Both men were reformist candidates in the election that was won by President Mahmoud Ahmadinejad. His re-election brought vast crowds onto the streets in demonstrations that were crushed by the state which said the unrest had been fomented by Iran's foreign enemies.

Mousavi's other daughter, Kokab, told opposition website Kaleme that security officials searched her sisters' homes for several hours and "took anything they thought might be of use to them along with my sisters."

With the reformists silenced, June's election is likely to be a contest between rival hardline factions in the Islamic Republic.

Mousavi, 70, Iran's prime minister in the 1980s, was treated for a heart problem in hospital in August.

(Reporting By Yeganeh Torbati in Dubai and Zahra Hosseinian in Zurich; Editing by William Maclean and Robin Pomeroy)