Afghan President Hamid Karzai Sunday cancelled a high-profile press conference in Kabul with new US Defense Secretary Chuck Hagel, with U.S. officials saying the event was dropped for "security concerns".

A palace official, who declined to be named, said however that the press conference had been cancelled because of "scheduling pressure", without giving further details.

Syria's National Coalition has for the second time in weeks postponed talks on the formation of an interim government, a senior member of the opposition grouping said Sunday, citing "deep rifts" on the issue.

The meeting was initially scheduled for last month in Istanbul but was postponed until Tuesday this week. It has now been delayed again, with a possible new date between March 18 and 20, said Samir Nashar.

Egypt's interior minister pleaded on Sunday for an end to "rumors" of police abuse, saying his forces had never fired a single shot at protesters since the start of the 2011 uprising.

Mohammed Ibrahim, who is facing an unprecedented strike by thousands of police officers across the country calling for his resignation, told reporters the media was waging an attack against the ministry and spreading lies.

The number of Syrian refugees, which just passed the million mark, could double or triple by the end of the year if no solution is found to the conflict, U.N. High Commissioner for Refugees Antonio Guterres said Sunday.

"Now if this escalation goes on and nothing happens to solve the problem we might have in the end of the year a much larger number of refugees: twice or three times the present level," he told reporters in Ankara.

Kenyans called Sunday for reconciliation after a disputed presidential election, but calm prevailed in the country the day after results were declared, in striking contrast to the aftermath of the 2007 polls.

Uhuru Kenyatta, who faces an international trial for crimes against humanity, was Saturday declared winner. But his main rival, Prime Minister Raila Odinga, has vowed to challenge the result in court.

Afghan President Hamid Karzai on Sunday criticized the Taliban for holding daily talks with the United States as they also launch suicide attacks that kill civilians and children.

The Islamist militants deny re-opening talks after they broke off tentative contact with the U.S. in Qatar in March last year due to failed attempts to negotiate a prisoner exchange.

As the Arab Spring blossomed two years ago, a heady breeze brought hopes of democracy, human rights and a better life to countries across the Middle East and North Africa, including Syria.

But while dictatorships fell in Tunisia, Egypt, Yemen and Libya, President Bashar Assad clung to power in Damascus, unleashing a brutal crackdown on what began as a peaceful pro-reform movement.

Global peace icon Nelson Mandela has spent the night in hospital after being admitted for a "scheduled medical checkup," with no official word on his condition Sunday.

His admission comes less than three months after being treated for a lung infection and gallstones.

Falkland Islanders hold a referendum on Sunday and Monday to send a message to the world that they want to stay British, although Argentina has already dismissed the vote as illegal.

Residents of the windswept archipelago in the South Atlantic have hoisted British and Falklands flags and even created a giant "YES" made of four-wheel drives ahead of the vote.

Venezuelan political parties begin registering candidates Sunday for a snap election on April 14, setting the stage for a bruising campaign to succeed the late president Hugo Chavez.

The national electoral council set the poll date on Saturday one day after Nicolas Maduro, Chavez's handpicked successor, was sworn in as acting president in a ceremony largely boycotted by the opposition, which slammed it as unconstitutional.