World leaders have expressed their sympathy and begun offering aid for the victims of a powerful earthquake that killed more than 90 people in central Italy.

Barack Obama, the US president, sent a message to the Italian people from Turkey, where he had begun a two-day official visit on Monday.

"We want to send our condolences to the families there and hope that we are able to get rescue teams in," he said.

The earthquake, which lasted about 30 seconds, caused many Renaissance-era and baroque buildings to collapse, including the dome on L'Aquila Cathedral, and forced Silvio Berlusconi, Italy's prime minister, to cancel a trip he had planned to Russia.

L'Aquila is the capital of Italy's Abruzzo region.

"I have cancelled my trip to Moscow because I think the situation is such that the presence of the head of government at the scene could be useful," Berlusconi told Italian television.

Dmitri Medvedev, Russia's president, sent his condolences from Moscow, telling Berlusconi that Russia was shocked by the tragedy and shares the sorrow of those who have suffered.

Vatican prayers

Nicolas Sarkozy, the French president, expressed his "deep sympathy" and solidarity in a message to Berlusconi.

“My thoughts are in particular with the injured, and with all those who have lost a loved one, to whom I ask you to pass on my most sad regards,” read the message released by his office.

Benedict sent a telegram to L'Aquila's archbishop with prayers for the victims [AFP]

Pope Benedict XVI sent a prayer from the Vatican in Rome, just 100km southwest of the earthquake's epicentre, to the victims in L'Aquila.

In a telegram to the archbishop of L'Aquila, Benedict said he was praying for the "victims, especially the children", killed in the earthquake.

The death toll is expected to rise as rescue teams continue to search the rubble for survivors.

The European Union, Austria, France, Germany, Greece, Israel and Russia had stepped forward with offers of aid, officials told the ANSA agency.

Although many buildings were reduced to rubble, Agostino Miozzo, the Italian civil protection head, said that aid was not immediately needed.