The attempt, for which no groups has yet claimed responsibility, was immediately denounced by some officials as another attempt to destabilise the interim government of Mr. Hamed Karzai.

The victims of Monday's explosion, including a child, had gathered on the street near the centre of town to greet the minister when the device went off in a roadside stall seconds before the arrival of his 50-strong convoy.

The Pakistan-based Afghan Islamic Press (AIP) reported that a fifth person died later in hospital.

The private news agency said up to 27 people had been injured in the blast, including schoolchildren who had come to welcome Fahim. A state of emergency has been declared at two hospitals in Jalalabad, the AIP said.

Fahim returned to the capital, Monday night and was received by a number of interim government officials at Kabul Airport, according to the official Iranian news agency IRNA.

He had left Kabul for talks with Nangarhar Province officials on security issues on Monday morning, when on his way from Jalalabad Airport to Nangarhar a strong bomb exploded as the car carrying him passed in a very near distance.

A Tajik Afghan, General Fahim is an influential and founder member of Afghanistan's Jam'iyat Eslami, the arch rival of Hekmatyar’s Hezb Eslami.

He has a record of fighting for the Iran and Russia-backed North Alliance forces for many years, serving as the late Ahmad Shah Mas’ood’s chief intelligence officer.

Fahim's senior lieutenant, Besmillah Khan, and corps commander of the northern city of Mazar Sharif, Atta Mohammad, were also in the convoy.

The device, described as "a deliberately detonated mine", was big enough to blow up at least two cars. It went off 50 meters ahead of the convoy, eyewitnesses reported, adding, "by all means, Fahim was the target".

The explosion also came less than two months after the interim administration's aviation minister, Dr. Abdol Rahman, was murdered at Kabul international airport.

Officials within the interim authority were accused of the murder, although a mob of Islamic pilgrims was also involved.

Security has been slowly returning to Afghanistan after the downfall of the Taliban at the end of last year, but ministers have warned that major problems remain.

Two similar rockets were fired at an ISAF compound early Sunday but no one was injured.

It was the first time peacekeepers were subject to rocket fire, though there have been several shooting incidents in recent weeks that have been blamed on disgruntled and unpaid northern alliance soldiers or common criminals.

Fahim was on a trip to meet with local commanders and tribal leaders to discuss, among other issues, a government program launched Monday to eradicate illegal poppy crops, offering farmers money to destroy the narcotic-bearing flowers.

Authorities have said they will destroy the crops if farmers do not comply.

The start of the program was linked to the outbreak of violence in several places, as poor poppy farmers protested that the government's cash offering falls far short of the narcotic's eventual market value.

In eastern Afghanistan, farmers opened fire on provincial officials surveying their fields along the Pakistan-Afghan Highway, killing one person and wounding four others, said Pir Haideri, an official with the Nangarhar provincial government in Jalalabad.