AMMAN/GENEVA (Reuters) - A planned Arab League visit to Syria on Wednesday to convey concerns over a crackdown on protests against President Bashar al-Assad's rule has been delayed, an Arab diplomat said, in a sign of Syrian unease at a toughening of the Arab position.

Pro-democracy demonstrations have gathered force in suburbs and rural areas across the country of 20 million despite daily reports of killings of civilians and heavy security in city centres.

Activists said 20 people had been killed on Monday and Tuesday and the United Nations estimates more than 2,200 people have been killed since unrest began in March.

Syria, which faces new sanctions from the European Union and wider Western pressure for Assad to go, had criticized the Arab League's decision late last month to urge an end to attacks on protesters and political and economic reforms.

An Arab diplomat at the Cairo-based League, who asked not to be identified, told Reuters late on Tuesday the visit by Arab League chief Nabil Elaraby had been delayed but not canceled. "It will take place when conditions permit," he added without elaborating.

Egypt's state news agency MENA said the delay followed a request from Syria, which gave no explanation and did not fix a new date for the trip.

The International Committee of the Red Cross said on Tuesday it was seeking access to thousands of demonstrators believed to be in informal lockups, a day after announcing Syria had opened its prisons for the first time.

ICRC chief Jakob Kellenberger said ICRC staff were making further visits to Damascus central prison, which has 6,000 inmates, both criminal and political.

"We have enough information to know that there are (other) places we have to see as early as possible," Kellenberger told a news conference on his return from Syria where he held talks with Assad.

Prison visits were an "ambitious and delicate exercise" for any country, Kellenberger said, noting that neither Egypt nor Bahrain had granted them despite repeated ICRC requests.

"The Syrian authorities are well aware, including President Assad, that for the ICRC this is a first step. And they are well aware of the fact that we want to go further and beyond," Kellenberger said, declining to be more specific.

The European Union, which imposed a ban on purchases of Syrian oil on September 3, was working on a new round of sanctions, the French foreign ministry said on Tuesday, to target entities that enable the "daily repression" against civilians.

At least one civilian was killed at a roadblock in the restive town of Rastan north of the city of Homs on Tuesday, activists said, while a local activist in Homs was quoted as saying the bodies of five murdered civilians were found there.

Rights activists said there were further arrests around the country on Tuesday with dozens of people detained in the Masbah al-Shaab neighborhood of the port city of Latakia, which has been besieged by troops and armor for weeks.

In the mostly Ismaili city of Salamiya east of Hama, a doctor, Taj Eldin Zino, was arrested by secret police as part of a campaign against dissidents in Syria's professional class. Security forces also raided houses in the southern town of Nawa.

Rights campaigner Adel al-Hafiya, a member of the Damascus Declaration umbrella opposition group, was arrested in the eastern city of Deir Zor, capital of a tribal province bordering Iraq's Sunni heartland, and taken to an unknown location, said the Local Coordination Committees, a grassroots activist group.

RIGHT TO TREATMENT

Kellenberger said he had made clear to Assad and Syrian officials at every level that all wounded and sick people must receive medical treatment, as required under international law. Continued...