A series of near-simultaneous explosions ripped through courthouse complexes Friday in three north Indian cities, with blasts going off in Lucknow, Varanasi and Faizabad, killing at least 13 lawyers and injuring dozens of other people, officials said.

Federal authorities blamed militants trying to spark unrest between India's Hindu majority and Muslim minority, though a legal group noted all the blasts came in a state where lawyers had decided earlier this year not to defend terrorist suspects.

At least nine lawyers were killed in three explosions in Varanasi, one of Hinduism's holiest cities, said Brij Lal, a top official in Uttar Pradesh state, where all three cities are located.

At least two of the bombs were attached to bicycles, police said.

In Faizabad, a pair of bombs killed four lawyers and injured 10 to 12 more, Lal said.

One of the bombs was rigged to a motorcycle, said R.N. Singh, a local police officer. Faizabad is near the town of Ayodhya, where Hindu extremists destroyed the 16th century Babri Mosque in 1992, sparking widespread Hindu-Muslim riots.

No deaths in Lucknow

There were no confirmed deaths in Lucknow, the state capital, though police said at least a few people were believed to be injured in twin explosions.

Lal said at least 40 people were believed to have been injured, most of them lawyers.

The blasts went off less than 15 minutes apart inside court complexes, though not in courtrooms, said Vipin Mishra, spokesman for the Home Ministry of Uttar Pradesh state.

Indian court complexes are crowded, chaotic places, with lawyers often setting up small outdoor "offices" in makeshift, open-walled shacks built in courtyards.

Decision not to defend terror suspects

"It's a conspiracy … This is the handiwork of some group that wants to disturb communal harmony in the country," the junior federal home minister, Sriprakash Jaiswal, told reporters. "They may have targeted the courts because large crowds gather in courthouses here."

But Padam Kriti, a spokesman of the Uttar Pradesh Bar Association, said "it looks like" the decision by the state's lawyers earlier this year not to defend terror suspects may have been behind blasts.

A series of terrorist bombings have ripped across India in the past two years. In August, a pair of explosions killed 43 people in the southern city of Hyderabad.

In July 2006, bombs in seven Mumbai commuter trains killed more than 200 people.