Investigators probing the serial blasts, which targeted lawyers in three cities of Uttar Pradesh on Friday afternoon, have prima facie ruled out the role of any homegrown group of jihadis.

Sources in state police said in Lucknow that the type of explosive devices used indicated that well-trained terrorists were behind the incident.

"All blasts were similar in nature. The possible use of ammonium nitrate to trigger the blast and electronic timer devices only proves that an old hand was involved," said an official.

Police officials claimed that while the bombs were low intensity in nature, the places where they were planted ensured that a large number of people were wounded.

"Only an expert in making and planting such devices will know when and where to plant the bomb," another officer said.

With this, the state police have, in a way, ruled out the role of Guru al-Hindi, which had sent E-mails to some television news channels on Friday claiming responsibility for the blasts. The group had claimed that it was a homegrown organisation of 'mujahideen,' which was annoyed at Indian politicians for their betrayal of Muslims.

It claimed that lawyers were targeted as they failed to protect the innocent. 'The next target would be the police, as it protects leaders of the Vishwa Hindu Parishad,' the E-mail added.

The police had on Friday night issued sketches of suspects who had planted bombs in Lucknow and Faizabad. While two sketches were released in Lucknow, one was released in Faizabad. A city-based cycle trader was questioned as a person had purchased a sports cycle from the shop around 1200 hours -- an hour-and-a-half before the blasts rocked the civil court premises in Lucknow.

Meanwhile, while the death toll remained at 15 overnight, police fear it could rise as some of the wounded in Faizabad and Varanasi were battling for life. "Septic and shock are the two factors which can increase the toll," claimed a police official.

A total of 15 people were killed and more than 80 injured as terrorists targeted the judiciary in Uttar Pradesh, triggering six powerful blasts at district courts in Lucknow, Varanasi and Faizabad within a space of 15 minutes.

Terrorists detonated the six explosive devices, placed on bicycles in the courts' premises, in a synchronised manner between 1315 hours and 1330 hours. However, in Lucknow, one blast failed to cause any damage while the other explosive was detected by the disposal squad and defused.

While officials have stopped short of naming any terrorist group so far, it is believed that Bangladesh-based Harkat-ul-Jehadi Islamia (HuJI) is behind the serial blasts.

Police said the terror strike could be seen as revenge by the banned outfit for the assault on its members, including the recent incident when lawyers manhandled three Jaish-e-Mohammed terrorists arrested in Lucknow last week.

If HuJI's role is confirmed at a later stage, Pakistan, or Pakistan-based terror outfits could not be directly blamed for the attacks. HuJI, which is mainly being run from Bangladesh, has managed to establish cells in the Uttar Pradesh and the outfit was responsible for previous major terror attacks.

All three court premises in Lucknow, Faizabad and Varanasi, targeted by the militants, had seen an incident of manhandling of militants or activists of anti-Ram temple in Ayodhya by lawyers.

Faizabad court premises witnessed an altercation between activists of a Babri Masjid organisation and lawyers. The local bar association had banned its advocates from taking up their case.

In 2006, the court premises in Varanasi witnessed the beating up of a Waliullah Khan, the main accused in the Sankat Mochan temple explosions.

On Saturday, panic gripped the Mughalsarai railway station in Chandauli district of the state following a low intensity explosion.

However, police sources at the state headquarters said it was a cracker which was bursted by some miscreants to create panic among the people. No one was injured in the explosion, police further said.

The cracker went off near the GRP rest room on the first floor of the railway station. Police have launched an intensive search operation inside the station. Railway sources maintained that train services on the route were normal.