Syrian Interior Ministry said Tuesday that 1,083 persons from across Syria who have been involved in recent riots have been immediately released after pledging not to repeat such acts that might harm the country and citizens, according to Syria's official news agency SANA.

The Ministry has recently appealed on those rioters to turn themselves to the ministry before May 15, vowing to release them without any punishment, Xinhua reported.

A UN report said Valerie Amos, Under-Secretary-General for Humanitarian Affairs and UN Emergency Relief Coordinator, Tuesday expressed her concern about the lack of humanitarian access to parts of Syria, including key cities where many protesters have reportedly been killed after clashing with security forces.

She voiced particular concern about the southern city of Deraa and the coastal cities of Latakia, Jablah, Baniyas and Douma.

Media reports say large numbers of protesters have been killed or detained in recent weeks as Syrian security forces respond to peaceful demonstrators that are part of a broader uprising across North Africa and the Middle East.

In her statement Amos noted that while her office has no confirmation of the number of people detained, injured or killed, "we remain concerned about alleged human rights violations."

A planned humanitarian mission by her office to Deraa on Sunday has not taken place, "despite repeated requests to the Syrian authorities for access," the Emergency Relief Coordinator said.

"The main objective of the mission was to independently assess the situation and plan a response if needed."

Secretary-General Ban Ki-moon has also spoken out in recent weeks about the situation in Syria and underlined the need for an independent investigation into the killings.

Amos said she was alarmed by reports of the deployment of tanks and the shelling of residential areas in some cities.

"In addition, ongoing security operations may be preventing the provision of basic social services," she said, citing the suspension and limited delivery of assistance to schools, clinics and community centers from the UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) as worrying.

"Of particular concern are reports that many wounded do not seek help in hospitals for fear of reprisals."

Syria has been gripped by more than seven weeks of protests amid calls for reforms. The protests have left more than a hundred army personnel and security agents killed across the country. Syria blamed the violent acts on "extremist terrorist groups," according to a Xinhua report.