DAMASCUS, Syria, Dec. 27 (UPI) -- United Nations Secretary-General Ban Ki-moon has voiced concern over use of heavy weapons and mortar shelling in the conflict in Syria.
Ban's comments came Thursday, amid intensified efforts to bring both sides of the conflict in Syria to a negotiating table in Switzerland, the United Nations said in a release.
"Further escalation of violence will only serve the agendas of those who see military means as the only way forward, at the expense of the Syrian people who have suffered enough already," Ban's spokesperson said in a statement.
Ban also spoke out against the use of "barrel bombs" -- oil drums filled with explosives and shrapnel and dropped from a plane -- saying they are "yet another appalling dimension to the fighting."
"All parties to the conflict must adhere to international humanitarian and human rights law," said the statement. "All civilians must be protected in any situation."
More than 100,000 people have been killed and 8 million more have been displaced due to the conflict that started in March, 2011.
The Syrian government is set to meet with opposition leaders for the first time Jan. 22 to discuss peace efforts. Representatives from more than 30 other countries will also participate in the conference.
Ban encouraged everyone involved in the Syrian conflict to "work immediately on reducing the levels of violence and focusing instead on a peaceful, political solution to the conflict."