RAMALLAH, WEST BANK - Israel on Monday released six Palestinian MPs from the Islamist Hamas movement who were detained in 2006 after Gaza militants captured an Israeli soldier, officials said.

Another MP was freed late on Sunday, bringing to 37 the total number of Hamas lawmakers released in recent months, including parliamentary speaker Aziz al-Dweik, who was set free in June.

Monday's releases were from the Ketziot prison in the Negev desert in southern Israel, witnesses said.

A spokesperson for the Israeli Prisons Authority said the lawmakers were released because the 40-month period of their administrative detention had expired. None was charged with anything.

It was unclear why Israel had decided to release the deputies at this particular time, since administrative detention can be prolonged indefinitely.

The MPs were among the more than 60 Hamas elected officials, including ministers, deputies and mayors, who were arrested by Israel as part of a crackdown on the Islamist group after the June 2006 capture of soldier Gilad Shalit by Gaza militants.

Fifteen Hamas MPs remain in Israeli detention, as do two from the Islamists secular rival Fatah party of Palestinian president Mahmud Abbas. One of the Hamas MPs freed on Monday told AFP the arrests were part of an Israeli attempt to prevent parliament from functioning and had nothing to do with the capture of Shalit.

'This confirms what we have said, that the campaign of arrests was basically intended to strike the Legislative Council and not for security as Israel had said,' Mahmud al-Ramahi said.

Hamas won a landslide victory in parliamentary elections in January 2006, the first it contested, securing 74 seats in the 132-legislature and routing long-dominant Fatah that got only 45.