In a suspected terror attack, 68 people, including some Pakistani nationals, were killed in explosions believed to have been set off by improvised explosive devices in two coaches of the Delhi-Attari special train for Lahore at Deewana near Panipat, about 100 km from Delhi.

Several people were also injured in the incident, which the Northern Railway said was a clear case of sabotage.

The two coaches, where all the deaths took place, were completely gutted and only the charred remains were visible.

The explosions in the train took place at 11.55 pm on Sunday night. The bi-weekly train left the Old Delhi railway station at 10.40 pm.

Preliminary examination of the material found in the two charred coaches of the Samjhauta Express has revealed that a deadly mix of kerosene, sulphur and potassium nitrate (low grade) was used for the explosives, official sources said on Monday. These materials were packed in clothes and a timer device in suitcases, the sources said.

Northern Railway General Manger V N Mathur, who reached the spot from Delhi, said two suitcases were recovered from the spot -- one on the rail track and one from the train.

Both the suitcases contained IEDs -- one of them also had incendiary material, either kerosene or petrol, he said.

He said he had talked to the gateman near Deewana station who told him that he had heard two distinct explosions. "From this evidence, we deduce that this is a clear case of sabotage," Mathur said.

After detaching the two coaches, the rest of the train left for Attari via Wagah. Superintendent of Police (Panipat) Mohinder Singh Sheoran said forensic experts from Madhuban were summoned.

A senior police officer said a Pakistani national has also given information to police regarding some explosive being planted on the train.

The official said the passenger was identified as Shamshuddin.

Two Railway Protection Force personnel who died in the blasts were identified as Kashmir Singh and Rajender Pal, both hailing from Punjab. While Singh was an ASI in RPF, Pal was a constable.

Pakistan President Pervez Musharraf and Prime Minister Manmohan Singh while condemning the "heinous" bombing of the Samjhauta Express from New Delhi vowed not to allow such acts of terror to derail the Indo-Pak peace process.

"We will not allow elements which want to sabotage the ongoing peace process to succeed in their nefarious designs," Musharraf said in a statement in Islamabad.

He underscored the need for Pakistan and India to move forward undeterred in the quest for dispute resolution and lasting peace in the region and expressed profound shock over the tragic loss of lives in the attack.

Dr Singh, who received a call from his Pakistani counterpart Shaukat Aziz, said India was committed to doing everything possible to ensure that perpetrators of the heinous act were punished.

"The prime minister declared India's abhorrence for this heinous terrorist act and reaffirmed our commitment to doing everything possible to ensure that its perpetrators are punished," the Prime Minister's Office said in a statement.

Dr Singh also conveyed his condolences to the Pakistani victims of the tragedy and indicated that steps were taken to provide all possible assistance for the injured and bereaved.

World leaders condemned the terror strike and expressed hope that it would not derail the Indo-Pak peace process.

Pakistani Foreign Minister Khurshid M Kasuri, who will arrive in Delhi on Tuesday on an official visit, said the response to the attack is that the "peace process must go on."

"We must deny terrorists any oppotunity. This act has to be condemned unreservedly," Kasuri said.

"It should act as an impetus for India and Pakistan to carry forward the peace process with even greater sincerity and a sense of purpose and direction," he said.

Describing the blasts as "a deliberate act of terrorism," the United States said such acts could only strengthen the resolve to defeat terror and achieve peace.

"The US government is shocked and deeply saddened by the tragic loss of lives caused by a deliberate act of terrorism," a US Embassy statement said in Delhi.

"Such acts can only strengthen the resolve of all well-intentioned people to defeat terror and achieve peace," it said adding, the US government extends its condolences to the victims of this "criminal act" and their families.

Expressing "profound grief" over the attack, Chinese Foreign Minister Li Zhaoxing sent his condolences to External Affairs Minister Pranab Mukherjee.

The European Union urged India and Pakistan to continue their peace dialogue despite the attack.

The German presidency of the EU said the attack was an act of "mindless violence clearly intended to disrupt the process of rapprochement between Pakistan and India."

Describing the bombings as "utterly shameful," British Foreign Office Minister Kim Howells said he was "shocked to learn of the devastating loss of life on the Samjhauta Express."

"I would also like to offer the governments of India and Pakistan whatever assistance they require, to bring to justice the perpetrators of this brutal attack," he said.

Bangladesh condemned the blasts as "heinous" and said it stood against "all forms of terrorism."

Japan said the blasts were "unforgivable" and "extremely vicious" and an "attack that targetted innocent people."

The train runs non-stop from Delhi to Attari where the passengers are shifted to the Samjhauta Express, which goes to Lahore after Customs and Immigration clearances.