British Prime Minister Tony Blair paid tribute Saturday to the seven "courageous" crew members of the space shuttle Columbia as leaders around the world mourned the astronauts' deaths.

Blair wrote letters to President Bush and Israeli Prime Minister Ariel Sharon to "express the government's sadness and offer his condolences," his office said. The Columbia crew included the first Israeli to fly in space.

Government officials around the world also expressed shock and sadness at the tragedy:

-- Belgium: Minister for Scientific Research Charles Picque expressed regret at the "immense human tragedy."

-- Canada: "The seven astronauts on board were accomplished women and men of great courage who put their extraordinary skills and knowledge to the service of humankind," Prime Minister Jean Chretien said in a statement. "Each one was a hero. Their contribution to science and space exploration will never be forgotten."

-- China: Chinese President Jiang Zemin sent President Bush his condolences on Sunday, saying the government and its people deeply regret the disaster and the death of Columbia's crew, the official Xinhua News Agency reported.

-- France: "In the name of the French people, forever a friend to the American people, I express to you the profound emotion and feeling of solidarity in the ordeal that all my compatriots are feeling," President Jacques Chirac in a letter to Bush.

-- Germany: In a letter of condolence to Bush, Chancellor Gerhard Schroeder paid tribute to the "courageous men and women" who died in the "terrible tragedy."

-- India: "For us in India, the fact that one of them (the astronauts) was an India-born woman adds a special poignancy to the tragedy," said Prime Minister Atal Bihari Vajpayee, referring to Kalpana Chawla. "Our hearts go out to the families of the bright young men and women who worked on that spacecraft."

-- Israel: "The state of Israel and its citizens are as one at this difficult time," Sharon's office said in a statement, after the death of Israeli astronaut Ilan Ramon.

-- Italy: Premier Silvio Berlusconi said he was "deeply shaken by today's tragedy. In the name of the Italian people and government, I express condolences and solidarity with the families of the victims and with the American people."

President Carlo Azeglio Ciampi also sent a messages of condolence to Bush.

-- European Union: Commission President Romano Prodi told Italian news agencies in Bologna the "enormous tragedy" occurred "in the service of progress, science and in this case, we can really say humanity."

-- Luxembourg: "The United States has written most of the most beautiful pages in the history of space conquest," Prime Minister Jean-Claude Juncker said in a message to Bush. "However this accident reminds us that conquest and the progress of science in the interests of humanity, which is so closely linked to it, remains a project full of dangers."

-- Mexico: The Foreign Relations Department "expressed its condolences to the government and people of the United States."

-- Poland: Prime Minister Leszek Miller sent letters of condolence to Bush and Sharon, government spokesman Michal Tober said.

"The astronauts gave their lives on the altar of science," Adam Michalec, a researcher at the Space Observatory of the respected Jagiellonian University in Krakow, southern Poland, told the Polish news agency PAP.

-- Russia: President Vladimir Putin called Bush to express his condolences, the presidential press service said. Putin said U.S.-Russian cooperation in space exploration made the accident even more tragic for Russians. Russia, which scrapped its Mir orbiting station in 2001, is deeply involved with the United States in developing the International Space Station, or ISS. Putin also sent a telegram of condolence to the Israeli prime minister.

-- Slovakia: President Rudolf Schuster sent a condolence telegram to Bush and Sharon and expressed sorrow over the tragedy, state-run news agency TASR said.

-- United Nations: "Because the exploration of space knows no national boundaries, the loss of the Columbia is a loss to all humankind," Secretary-General Kofi Annan said.

-- Vatican City: Pope John Paul II received the news with great sadness and prayed for the astronauts during services, a Vatican official said on condition of anonymity.