Nearly 40 people were injured when bombs exploded Sunday in two cinema halls here screening the controversial film "Jo Bole So Nihal", causing panic across the city and prompting authorities to sound an alert.

Police officials said the blasts -- which occurred almost simultaneously at 8.30 p.m. at the Liberty theatre and the Satyam multiplex located within a few kilometres of each other in west Delhi -- were caused by crude bombs.

However, authorities said none of those injured were in serious condition.

Police evacuated people from the popular PVR Anupam multiplex at Saket screening "Jo Bole So Nihaal". Night screenings were also cancelled at the Wave in Noida near Delhi, and cinemas in Agra in Uttar Pradesh as well as Faridabad in Haryana.

Home ministry officials said an alert was also sounded in Punjab and Maharashtra and security checks been intensified at Delhi's borders.

Minister of State for Home Shriprakash Jaiswal said there was a "conspiracy" behind the blasts while Delhi Chief Minister Sheila Dikshit urged people not to panic.

Sikh organisations had called for a ban on "Jo Bole So Nihaa", saying it depicted the community in a poor light. Distributors voluntarily withdrew the film from cinemas across Punjab last week following the protests.

Following the blasts at Liberty theatre at Karol Bagh and Satyam multiplex in nearby Patel Nagar, terrified viewers ran screaming out of the theatres.

Most of the wounded drove themselves to nearby hospitals, while anxious relatives made a beeline for the halls to search for their kin.

Ambulances, fire brigade personnel and policemen rushed to the theatres and TV channels beamed footage of bleeding men and women being treated at several hospitals.

Dikshit, who visited Satyam, said the law and order situation in Delhi was becoming a cause for major concern. She noted the blasts had occurred despite both theatres being equipped with metal detectors at their entrances.

Minister of State for Home Jaiswal, who visited Liberty, said: "There can be protests but one should not target innocent people in this manner. But it is very difficult to prevent such attacks."

Jaiswal said the home ministry had not received any intelligence reports about possible attacks on halls screening "Jo Bole So Nihaal".

Referring to the blast at the Liberty theatre, Delhi Police Commissioner K.K. Paul said: "The explosive device, which was kept under a seat in the seventh row of the ground floor, did not contain shrapnel which is usually found in such bombs."

The blast at Satyam occurred in a toilet, police officials said.

O.P. Sharma, the manager of Liberty cinema, said the blast just after the show's interval. The row where it occurred was unoccupied as the tickets for it had not been sold.

"I suspect extremists are behind this as we had earlier received threats," Sharma told.