British Prime Minister Tony Blair

"It is particularly barbaric that this has happened on a day when people are meeting to try to help the problems of poverty in Africa, the long-term problems of climate change and the environment. Whatever they do, it is our determination that they will never succeed in destroying what we hold dear in this country."

Blair (Speaking on behalf of world leaders at the G8 Summit)

"We condemn utterly these barbaric attacks. We are united in our resolve to confront and defeat this terrorism."

U.S. President George W. Bush

"This morning I have been in contact with the Homeland Security folks. I instructed them to be in touch with local and state officials about the facts of what took place... in London and be extra vigilant."

Russian President Vladimir Putin

"Wherever such inhuman crimes occur -- in London, in New York or in Moscow -- we must unconditionally condemn them and unite all civilised countries in the struggle against international terrorism."

German Chancellor Gerhard Schroeder

"I and all the leaders of the G8 summit condemn in the strongest possible terms these incidious acts, which have cost the lives and health of many innocent people. We agree that the international community must do everything and use all available means to fight terrorism together."

Irish Prime Minister Bertie Ahern

"This is terrorism and violence perpetrated against ordinary people ... it's just a black mark on society, a devastating blow against people... This is a huge emergency. A terrible, sad day."

Pope Benedict XVI

Condemned the blasts in London as "barbaric acts against humanity".

Danish Prime Minister Anders Fogh Rasmussen

"Once again, we witness the barbaric assault of terrorists on completely innocent people -- civilians, women and children. The terrorists use dread and fear as political pressure. We must and will not permit this. We must never bend to terrorists and they must never be allowed to reach their goals by spreading death and destruction."

Spanish Prime Minister Jose Luis Rodriguez Zapartero -- in a statement from his office.

"Spain, which has suffered the scourge of terrorism, both national and international for years, offers its immediate and unconditional help, as well as its full support to the United Kingdom to pursue the criminals that have carried out such a repulsive attack."

Dutch Prime Minister Jan Peter Balkenende

"Terrorism is an evil that threatens all the countries in Europe. Vigorous cooperation in the European Union and worldwide is crucial in order to meet this evil head on."

Saudi Arabia's Social Affairs Minister Abdulmohsen Al-Akkas

"It is a heinous act. I don't know who did it. I condemn it in the strongest possible terms and I offer my sympathies to the families".

Hungarian Prime Minister Ferenc Gyurcsany

"Violence of any sort is unacceptable, any action outside the framework of democratic institutions is unacceptable. It's not acceptable that innocent people, children or adults, should suffer in London, or anywhere else in the world, because of the unacceptable terror of a few."

EU Foreign Policy Chief, Javier Solana

"A terrible event can happen at any time. We cannot let down our guard. We are working every day, and in a coordinated way in all the EU countries." "Unfortunately there are times when one cannot prevent one (an attack of this sort) happening."

EU Commisioner for Justice and Security, Franco Frattini

"We have the tragic confirmation that terrorism has once again hit the heart of Europe and hit a country that holds the presidency of the (European) Union and the G8."

Pakistan President Gen. Pervez Musharraf

Said it is "imperative that we stand together ... to eliminate this menace."

U.N. Secretary-General Kofi Annan

"These vicious acts have cut us all to the core, for they are an attack on humanity itself... Today, the world stands shoulder to shoulder with the British people."

European Parliament President Josep Borrell

"We will never let atrocities or terrorism defeat the values of peace and democracy," he said

French Prime Minister Dominique de Villepin

"It is a drama for Great Britain. It is a drama for all of Europe."

Iraqi Prime Minister Ibrahim al-Jaafari -- in a message to Tony Blair

"While I am expressing my deep sorrow to you and through you to the British people and families of victims, I confirm to you our deep will to rid the evil of terrorism in any country as it appears,"

Italian Premier Silvio Berlusconi

"A band of fanatical criminals has made London and Britain pay a high price for hosting the G-8... Terrorism will not prevail if we stand united with determination."

Quotes compiled by Reuters / AP