Imphal, Jan 5 (IANS): A ruling Congress party office came under a powerful grenade attack late Wednesday in election-bound Manipur, even as seven influential separatist groups called for a ban on all poll meetings and campaigning by the ruling party.

A police spokesperson said unidentified militants lobbed a grenade at a Congress party election office at Singjamei on the outskirts of capital Imphal around 8.45 p.m.

"Nobody was injured in the attack as the office was closed by then. A parked car was damaged in the impact of the blast," the official said.

Elections to the 60-member house takes place Jan 28.

Meanwhile, seven militant groups, including the outlawed United National Liberation Front (UNLF), the People's Liberation Army (PLA) and the People's Republic of Kangleipak (PREPAK), have called for a ban on all election meetings and campaigning by the Congress candidates in the state.

An emailed statement signed by seven militant groups warned of dire consequences if their diktat was violated.

Militant groups in past elections as well targeted the Congress candidates and issued similar warnings.

There are more than 20 rebel armies active in Manipur, a state bordering Myanmar, with demands ranging from secession to greater autonomy.