U.S. President Barack Obama called President Mohamed Morsi to warn him that the voices of all Egyptians must be heard as a political crisis escalates, the White House said Tuesday.

Obama placed the call from Tanzania, on the final stop of his African tour and told him Washington was committed to "the democratic process in Egypt and does not support any single party or group," the official said.

Fugitive U.S. intelligence leaker Edward Snowden on Monday accused U.S. President Barack Obama of "pressuring the leaders" of countries from which he has sought protection.

In his first public announcement since fleeing Hong Kong eight days ago, he accused Obama of ordering his Vice President Joe Biden to put pressure on leaders of countries where he was seeking asylum.

U.S. President Barack Obama on Monday called on the countries bordering Democratic Republic of Congo to stop backing armed groups there.

"The countries surrounding Congo, they have got to make a commitment to stop supporting armed groups," Obama told a press conference in the Tanzanian commercial capital, where he is wrapping up a three-nation African tour.

U.S. leaker Edward Snowden has applied for asylum in Russia and President Vladimir Putin said on Monday he was welcome to stay as long as he stopped leaking U.S. intelligence reports.

On Sunday night, Snowden applied for political asylum at the consulate office of the Sheremetyevo airport, where he had been staying for more than a week in legal limbo, a foreign ministry official told Agence France Presse.

U.S. President Barack Obama touted his new climate change proposal in his weekly address Saturday, calling for Americans to lead the charge against the warming environment.

"Those who already feel the effects of a changing climate don't have time to deny it -- they're busy dealing with it," said Obama in his pre-recorded address on radio and the Internet.

U.S. President Barack Obama was "deeply humbled" by a visit to the cell where Nelson Mandela spent years as a prisoner, in a solemn homage Sunday to the critically ill hero he was unable to see in Pretoria.

The U.S. leader paid tribute to Mandela and other anti-apartheid inmates of Robben Island, who "refused to yield" in the face of racist white minority rule.

Police fired stun grenades on Saturday at hundreds of protesters rallying against President Barack Obama's visit to South Africa, an Agence France Presse correspondent said.

At least three bangs were heard as police tried to move the demonstrators away from a university campus where Obama is expected to hold a town hall event later in the day.

U.S. President Barack Obama spoke to the wife of ailing anti-apartheid hero Nelson Mandela by telephone on Saturday during a visit to South Africa, a White House statement said.

"I expressed my hope that Madiba draws peace and comfort from the time that he is spending with loved ones, and also expressed my heartfelt support for the entire family as they work through this difficult time," Obama said in the statement, using Mandela's clan name.

U.S. President Barack Obama said Thursday he would not "scramble jets" to intercept any flights carrying fugitive leaker Edward Snowden and scoffed at spending political capital to win him back from Russia.

Obama, questioned in Africa on the latest twists of the international spy drama involving Snowden and his exposure of U.S. phone and Internet surveillance programs, did however admit he was worried about what other secrets might leak.

America's first black president Barack Obama will acknowledge the historic stain of slavery and honor Senegal's democratic resilience in an unstable region Thursday, at the start of an African tour.

Obama stepped off Air Force One into the African night late Wednesday in Dakar to launch a three-nation trip designed to fulfill neglected expectations for his presidency on a continent where he has deep ancestral roots.