The Red Cross announced on Tuesday that it will be allowed to visit a second Syrian prison as localised violence grips the country.
International Committee of the Red Cross president Jakob Kellenberger said that it will visit a prison in Aleppo in May. It toured a Damascus jail in September.
Addressing a news conference at the ICRC's HQ in Geneva, Mr Kellenberger appealed for £16.4 million to quickly scale up aid for the 100,000 "particularly vulnerable" Syrians who are dependent on Red Cross and Syrian Arab Red Crescent support.
He said tens of thousands of people are currently sheltering in public buildings or other people's homes.
"Our priority is to improve living conditions and to restore public services for up to 1.5 million people affected by the fighting," Mr Kellenberger said.
The Red Cross chief said insurgents have turned to localised attacks since the arrival of about 40 UN observers.
"The type of the violence has changed - you no longer have big battles like in Homs, but more guerilla and bomb attacks," he said.
More observers are preparing to go to bring the total to the UN-approved limit of 300.
The Syrian government hailed a "remarkable" turnout in Monday's parliamentary elections, which it said were proceeding "normally."
But US State Department spokesman Mark Toner said: "It is not possible to hold credible elections in a climate where basic human rights are being denied."