DHAKA (AFP) - Bangladesh has arrested more suspected militants ahead of next week's elections, a police officer said Friday, bringing to 23 the number of people held as part of a pre-polls crackdown. The South Asian nation will hold its first elections in seven years on Monday amid an unprecedented security operation to counter terrorist attacks and vote-rigging. Eight men were arrested following raids in the northern Govindaganj district where police also seized a cache of explosives " big enough to make 300 grenades " that could cause "serious damage," area police chief S.M. Shibly said. "It is the biggest haul of explosives we've found in the recent months. We are conducting massive operations across the region to find out other members of the group," he said.The men are suspected of belonging to the banned group, Jamayetul Mujahideen Bangladesh (JMB). More than 50,000 military personnel have been deployed across the country, 600,000 police officers are manning polling booths and the country's elite Rapid Action Battalion has undertaken a massive anti-crime crackdown since campaigning began two weeks ago. Earlier this week, two suspected JMB militants were arrested in southeastern Comilla district after a raid uncovered a cache of grenades hours after Bangladesh Nationalist Party chief Khaleda Zia held a campaign rally nearby. Zia, a former premier, has said extremists are plotting to kill her ahead of the elections, which will end two years of rule by an army-backed government. Bangladesh has been hit by a series of attacks by the extremists' groups in recent years " including 400 blasts on one day in August 2005 by the JMB. The JMB has been virtually silent under the current government but analysts fear it has regrouped. The deputy chief of the Rapid Action Battalion, Colonel Gulzar Uddin, said a big attack was unlikely before the polls. "It appears that they are trying to regroup, but we don't think they have the capacity to make major attacks ahead of the polls," he said.