U.S. President Barack Obama offered "warm wishes" on behalf of the American people to newly elected Pope Francis I on Wednesday, hailing the Argentine as "the first pope from the Americas."

"As a champion of the poor and the most vulnerable among us, he carries forth the message of love and compassion that has inspired the world for more than two thousand years, that in each other we see the face of God," he said.

The European Union offered its "sincere congratulations" Wednesday to the newly-elected Pope Francis I of Argentina, urging him to promote peace, solidarity and human dignity in a rapidly changing world.

"On behalf of the European Union, we convey our sincere congratulations on your election," EU President Herman Van Rompuy and European Commission head Jose Manuel Barroso said in a joint statement after Jorge Mario Bergoglio was named as the church's first Latin American pontiff.

Argentina's Jorge Mario Bergoglio was elected Pope Francis I on Wednesday, becoming the first Latin American pontiff in a surprise decision that signaled a desire for a more open Catholic Church.

The 76-year-old moderate emerged smiling on to the balcony of St Peter's Basilica to cries of "Long live the pope!" as tens of thousands of pilgrims cheered, cried and applauded.

Thailand on Wednesday denied accusations its sailors shot Rohingya boat people fleeing sectarian strife in Myanmar, after a rights group urged a probe into the alleged deaths of at least two migrants.

Survivors of the alleged incident on February 22 told Human Rights Watch that sailors opened fire on around 20 Rohingya migrants, killing two of them, as they jumped overboard to escape custody after drifting into Thai waters.

A suicide bomb exploded in crowds at a traditional horse-back game of buzkashi in northern Afghanistan on Wednesday, killing at least six people, police said.

"The suicide attacker detonated himself at the end of the match in Imam Sahib district this evening. Six people have died," Abdul Khalil Andarabi, police chief of Kunduz province, told Agence France Presse.

All traffic through an Alpine rail tunnel linking Switzerland and Italy was halted Wednesday due to a bomb threat, police and the national Swiss rail service said.

"The bomb threat was received at 11:15 am (1015 GMT) and all the traffic has been interrupted" through the Simplon tunnel linking the Swiss town of Brig with Domodossola in Italy, said Marcus Rieder, a police spokesman in the southern Swiss canton of Valais.

Pakistani police have arrested around a dozen children, some as young as 10, suspected of being used to plant bombs for separatist militants, officers said Wednesday.

The arrests were made in raids over the past 24 hours, local police chief Mir Zubair Mahmood said while presenting the children at a news conference in Quetta, the capital of the restive province of Baluchistan.

A Frenchman who ripped a Muslim woman's veil off her face as she strolled in a fairground was Wednesday given a five-month suspended prison sentence and ordered to compensate his victim.

The 30-year-old man, who admitted charges of aggravated assault, had justified the September 2012 attack at the time as an attempt to uphold a controversial law banning women from wearing niqabs, face-covering veils, in public.

U.S. President Barack Obama said in an interview aired Wednesday that a U.S. pope would be just as effective as one of another nationality.

"It seems to me that an American pope would preside just as effectively as a Polish pope or an Italian pope or a Guatemalan pope," Obama said, though noted he had no idea how seriously such an issue was being discussed.

President Barack Obama entered the fray Wednesday on cyber attacks from China, saying some intrusions affecting U.S. firms and infrastructure were "state sponsored."

The comments appeared to step up the rhetoric against China following similar remarks from other members of the U.S. administration.