"The secretary-general reiterated his calls for an immediate end to violence against and mass arrests of peaceful demonstrators in Syria, and for an independent investigation of all killings that happened during the protests, including the alleged killing of military and security officers," said a UN readout released by Ban's spokesperson.

He added that it was critical to respect the human rights of the population.

"The secretary-general also encouraged full and early implementation of all the reform measures announced by the Syrian government, and emphasized the importance of engaging a genuine inclusive dialogue and a comprehensive reform process," said the UN readout.

On humanitarian needs of the population, Ban said they "should be urgently met."

"Expressing deep concern at the humanitarian implications of the latest developments in a number of Syrian towns, he called on President Assad to immediately grant access to the United Nations in order to assess the humanitarian needs of the affected civilian population," said the UN readout.

The UN readout added that the secretary-general "appreciated President Assad's willingness to consider such an assessment to Deraa."

Syria has been witnessing unprecedented anti-government protests that erupted six weeks ago in Daraa calling for releasing 15 teenagers who had been arrested for writing anti-regime graffiti on a wall. The protests have spread into other parts of the country including the capital Damascus.