Reuters, DHAKA - Bangladesh's main political parties are threatening to launch a movement defying the state of emergency and to boycott elections scheduled for later this year if their top leaders are not freed soon.

The parties are the Awami League and Bangladesh Nationalist Party (BNP) led by former prime ministers Sheikh Hasina and Begum Khaleda Zia respectively.

Both women have been in jail since last year on corruption charges, and if convicted will be barred from contesting the elections.

Following a meeting late on Monday, the Awami League said a planned nationwide signature campaign and hunger strike to press for Hasina's release could turn into a mass movement to press for her freedom.

"We urge the government to release Hasina by April 4 to avoid the movement," said senior Awami leader Tofayel Ahmed, hinting at possible street protests and other actions now banned under the emergency.

Retired brigadier-general Hannan Shah, a senior BNP leader and staunch Khaleda loyalist, said his party was also prepared to take "any appropriate action" to get her out of jail.

"We will leave no stone unturned to force the release of our beloved leader and will not take part in elections while she is behind bars," Hannan told BNP members on Monday.

Political analysts say if one group defied emergency rule, others would swiftly follow suit.

The government has showed no sign of yielding yet.

Headed by former central bank chief Fakhruddin Ahmed, the government says it will end the emergency "at an appropriate time" ahead of elections promised for late 2008.