* ICRC seeks access to besieged towns
* Says confidence-building measures might pave way for peace
* Ready to play neutral role in any prisoner exchanges
By Stephanie Nebehay
GENEVA, Jan 20 (Reuters) - The Red Cross is ready to deliver aid to besieged towns in Syria and facilitate prisoner exchanges if the warring sides agree to confidence-building measures at peace talks in Switzerland, a senior official told Reuters on Monday.
Syrian Foreign Minister Walid al-Moualem said on Friday he had handed Russia plans for a ceasefire with rebel forces in Syria's biggest city, Aleppo, and was ready to exchange lists on a possible prisoner swap..
"The ICRC has a very clear stand on this. We can offer to play a role of neutral intermediary in the event of an exchange of prisoners provided this is done according to our modalities," Robert Mardini, head of operations for the Near and Middle East at the International Committee of the Red Cross (ICRC), told Reuters in an interview in Geneva.
The independent aid agency hoped that an international conference this week would address the "catastrophic" humanitarian situation after nearly three years of conflict that the Syrian opposition says has killed more than 130,000 people and uprooted millions.
But the talks were thrown into doubt on Monday, with the opposition threatening to pull out over a last-minute United Nations invitation to Iran to take part.
Mardini said scaling up humanitarian aid to all Syrians would form part of confidence-building measures that might "pave the way for a political resolution of this conflict".
"So access to besieged areas, whether besieged by the governmental forces or the armed opposition groups, visiting detainees even if there is no exchange, accepting the impartiality of medical aid for all Syrians, is also something that could be confidence-building measures," he said.
Besieged areas including Mouadamiya and Yarmouk in the Damascus countryside, the Old City of Homs, parts of Aleppo and the whole of eastern Ghouta are of great concern, amid reports of some civilians eating just "grass and olives", he added.
"It is important to say that we are ready to take some calculated risks," Mardini said.
"We don't put as a precondition that we want a total cessation of hostilities before we go in," he said.
Despite fighting last year, ICRC engineers repaired a vital water pipeline between Homs and Hama, he noted. "When you have 1.3 million people who will get water, you can accept a higher level of risk," he said.
But the ICRC prefers humanitarian pauses or ceasefires to humanitarian corridors which must be enforced, Mardini said.
"We are not big fans of humanitarian corridors, because history has shown they are very complex. It maybe seems clear and easy on paper but the implementation is very complex.
"With humanitarian pauses, there is a consent of both parties to stop fighting, so Syrian Red Crescent ambulances can go and help people go out, that would be positive. And they can provide food, water and medical supplies," he said.
The ICRC is not taking part in the ministerial meeting due to open in the Swiss resort of Montreux on Wednesday, nor in direct talks between representatives of the Syrian government and opposition, scheduled to start on Friday, he said.
But it is in touch with international mediator Lakhdar Brahimi, according to Mardini, who accompanied ICRC President Peter Maurer to Syria for Jan. 11-13 talks with top ministers.
"We have discussed visas, we are discussing visiting detainees and access to besieged areas. And of course all the allegations of arrests that families come to our office to ask about, the whereabouts of their loved ones," Mardini said.
"We are in a waiting mode. We hope that promises will translate into tangible results for the detainees," he said.
ICRC officials have visited only two prisons, in Damascus and Aleppo, since Syria first allowed it access in Sept 2011.
In all, the ICRC is helping to provide clean water to 20 million people in Syria and has also provided emergency food and other supplies to 800,000 people.
But it has been stymied by both sides from delivering life-saving medical care to the wounded and the sick, he said.
"Today we know that there are more than half a million wounded persons who unfortunately don't have access to medical care. This is of course something that is unacceptable.
"Persons are dying not only because they are wounded, they are dying because of the lack of access to basic primary health care services," he said.
The ICRC aid operation in Syria is its largest worldwide, with a budget of 105 million Swiss francs ($115.46 million) this year. It deploys 200 staff there, including 35 expatriates.
Three ICRC staff kidnapped by unidentified gunmen last October near the northern town of Idlib remain missing.
($1 = 0.9094 Swiss francs) (Reporting by Stephanie Nebehay; Editing by Mark Trevelyan)