THE RISK is still there:

One year after the worst terrorist attack in Spanish history, the Spanish police continue to uncover and thwart new plots involving Islamic militants, according to senior Spanish intelligence and law enforcement officials.

Despite sweeping measures to improve their ability to investigate potential terrorism since the bomb attacks that killed 191 people on March 11, 2004, and one police officer in the aftermath, the officials estimate that there are hundreds of people scattered in cells around the country committed to attacking centers of power in Spain.

The police have found indications of a cell of Pakistanis they suspect was planning an attack on a high-profile target in Barcelona. The police also found evidence of a cell of North Africans in Madrid that apparently wanted to attack Madrid's high court, the officials said.

"We have been lucky that our investigations have managed to abort other plots before acts of terrorism took place," Juan Fernando López Aguilar, the justice minister, said in an interview. "That means the threats have not disappeared."

López Aguilar added that Spain had detained about 1,000 people suspected of being connected to the Madrid bombings and other potential terrorist activities in the past year. Most have been released.

Spain is still hunting for at least half a dozen suspects in the bombings, although they are probably outside the country.

"The great majority of the perpetrators are identified, dead or in prison," said a senior intelligence official at the Civil Guard, a police force with military and civilian functions. "But we cannot say that we have all of them. There are questions that remain unclear. The most important is: Who masterminded March 11?"