HAVANA -- A small explosion in front of a church in Old Havana on Saturday caused no injuries or damage but has fueled fears of violence surrounding the pope's visit here next month.

``The explosion was strong. People felt it,'' said Miguel Saludes, secretary of the La Merced church near the Havana docks. He said the blast caused no damage to the building, an imposing yellow-orange structure built in 1792 that is a popular stop on tours.

There were no reports of arrests, and there was no immediate reaction from the Cuban government.

Church spokesman Orlando Marquez said the explosive device was about four inches long. No other details were available.

Uniformed police left the scene a few hours after the explosion. But a church official said security agents in civilian clothing stayed and attended a morning Mass, which was held as scheduled.

The church's five priests were asleep in a building next door when the device exploded.

Cardinal Jaime Ortega, interviewed Saturday after presiding over a gathering of 1,200 Roman Catholic youths, said the explosion was troubling but that he doubted it would affect security measures for the Jan. 21-25 visit by Pope John Paul II.

``It appears to have been a small device, of simple construction,'' Ortega said. ``It provoked no damage -- only alarm.''