Prime Minister Tony Blair is to attend a memorial service for the victims of the train bombs in Madrid.
The bombings killed 201 people
Mr Blair's official spokesman said the Prince of Wales would also attend the service in Madrid on Wednesday.
More than 200 people died in a series of blasts on 11 March, which left more than 1,200 injured.
Ten bombs exploded on four trains during the busy morning rush hour. A total of 14 people have been arrested over the blasts.
After the service in the morning, Mr Blair will hold meetings in Spain before travelling
on to Lisbon for meetings with the President and Prime Minister of Portugal.
His spokesman declined to confirm whether he would also meet Spain's prime minister-elect Jose Luis Rodriguez Zapatero , who has been an outspoken critic of the Iraq war.
Mr Zapatero snatched a surprise victory in the general election just days
after the Madrid outrage.
The tragedy has led to calls for improved security in the UK to tackle such atrocities and more police have been deployed to railway stations.
Foreign Secretary Jack Straw is meeting European colleagues on Monday to discuss measures to combat international terrorism in the wake of the bombings.