PESHAWAR (AP): A bomb exploded at the mausoleum of a 17th century Sufi poet in northwestern Pakistan on Thursday, showing the gulf between hard-line Muslims and many in the region who follow a traditional, mystical brand of Islam.

A letter delivered to the management of the mausoleum of Sufi poet Rehman Baba on the outskirts of Peshawar warned against its perpetration of ``shrine culture'' three days before the attack, said Sahibzada Mohammad Anees, a top government official in the city.

The letter also noted that women were coming to pray at the shrine, he said.

Many Pakistanis like to pray at the tombs of mystics and holy men, something opposed by hard-line Muslims because they believe it is un-Islamic. The extremists also believe Islam prohibits men and women from mingling unless they are husband and wife or close relatives.

The blast before dawn early Thursday damaged one corner of the shrine. No one was injured.

Baba's poems were laced with Islamic mysticism or Sufism and remain popular among the Pashtun people of northwest Pakistan and Afghanistan. A professor at Peshawar University told a local TV station that in many Pashtun homes, Baba's poems are kept alongside the Islamic holy book, the Quran.

In recent years, Islamist militants have increased their hold over much of northwest Pakistan and are increasingly seen threatening other areas of nation of 170 million people.