In a statement released by his spokesman, the Secretary-General, who is travelling in Moscow, said he was "appalled" by the incident, noting that it came amid a concerted international effort to convene a peace conference on the Middle East.

"Brutal and wilful killing of innocent civilians can never be justified, no matter what the political objective," the statement said. "Every effort must be made to bring to justice those responsible for this cruel act."

The Secretary-General urged those committed to finding a political solution in the Middle East to stay the course. "The enemies of peace should not be allowed to derail this process," the statement stressed.

Mr. Annan also extended his condolences to the families of the victims and to the Government of Israel.