Raipur, Sep 1 (IANS): Security forces foiled a bid by Maoist ultras to trigger a massive blast in Bijapur district by defusing a powerful explosive device buried beneath the road surface, police said Saturday.

"A search team of security forces recovered a 40 kg bomb from Basaguda Road between Timmapur and Murdanda Friday evening," Bijapur district Superintendent of Police Prashant Agrawal said. The device was later safely defused, he added.

"Three 'tiffin bombs' of 5 kg each were also recovered from near Tikler on Gangalur road," Agrawal said.

Sources said a joint team of district police and Central Reserve Police Force was on a routine search operation when the device was detected, hidden under a mound of soil.

Digging a little, the search party uncovered a 40 kg device attached to a detonator.

Another search team also recovered three "tiffin bombs" of 5 kg each on Gangalur road near Tikler in the same district.

In neighbouring Sukma district, a team on patrol, comprising Central Reserve Police Force troopers also, Friday night spotted a group of Maoist guerrillas in the jungles of Koyabekur in Dornapal area, about 600 km south of state capital Raipur.

The two sides exchanged fire for nearly half an hour, after which the insurgents retreated into the forest under cover of darkness.

No casualty was reported on either side.

"A joint team of district police and CRPF had left for a search operation under the leadership of Sukma Sub Divisional Officer of Police (SDOP) Lakhan Patne late Friday evening. They were fired upon by Maoist guerrillas in the jungles of Koyabekur in Dornapal area. The security forces returned the fire, forcing the insurgents to retreat," Sukma SP Abhisek Sandilya told IANS Saturday.