GENEVA (Reuters) - The besieged Syrian town of Daraya, a rebel-held suburb of Damascus where President Bashar al-Assad has refused to allow aid to starving Syrians, got its first U.N. aid convoy since 2012 on Wednesday.

People walk past a convoy carrying humanitarian goods waiting to enter the besieged area of Moudamiya Al Sham, at the last checkpoint which is controlled by Syrian government forces, in the suburbs of Damascus, Syria June 1, 2016. REUTERS/Omar Sanadiki

Russia’s Defence Ministry said a temporary ceasefire, which it called a “regime of calm”, had taken effect from June 1 for 48 hours in the Damascus suburb to allow for the distribution of humanitarian aid to civilians.

In a short statement, the ministry said it had coordinated the “regime of calm” with the Syrian authorities and with the United States “to secure delivery of humanitarian aid to the population”. It took effect from midnight, the ministry said.

Syrian opposition negotiator Basma Kodmani said the aid to Daraya and nearby Mouadamiya, another besieged zone, was only a first step that had come about as a result of extreme international pressure on the Syrian government, and substantial change was still needed.

“The first lesson is that pressure and ultimatums are the only way we get the regime to hear anything,” she said. “We will obviously not be content with one convoy as happened today.”

The trucks got through on the day when the Syrian government faced a deadline to admit aid by road or risk having air drops imposed by the countries of the International Syria Support Group (ISSG), which includes Syria’s ally Russia.

“If we don’t see substantial change, then we definitely are waiting for those air drops to happen as a sign of the seriousness and the commitment of the international community,” Kodmani said.

The aid to Daraya contained medical supplies, vaccines, baby milk and nutrition items, but no food. A U.N. spokeswoman said it was hoped that food would follow in subsequent convoys.

The United Nations has previously warned that children could die of starvation because of the “horrendously critical” situation in Daraya, Mouadamiya, and a third area, al Waer, which did not receive any aid on Wednesday.

The U.N. estimates 4,000 civilians are still in Daraya, which is close to a large air base and has been besieged and regularly bombed since 2012.

Last month, a U.N. convoy was turned away at the gates of Daraya because soldiers refused to let baby milk into the town, the U.N. said.

Staffan de Mistura, the U.N. mediator of Syria peace talks, has said he wants to see improved humanitarian access, as well as a renewed lull in the fighting, before announcing a date for a new round of peace talks in Geneva.

The ISSG humanitarian taskforce will meet on Thursday to review progress on getting aid to more than a million people in besieged and hard-to-reach areas. Kodmani said they should not be fooled by the Syrian government allowing in one convoy “to defuse the pressure”.

“If it is going to become tit-for-tat, a convoy for a date, this is not going to work,” she said.

A return to peace talks, after a last round which ended on April 28 amid a spiral of violence, was likely if the international community kept up the pressure on Assad’s government, she said.

The opposition High Negotiations Committee has proposed a nationwide truce during the month of Ramadan, which would restore the “cessation of hostilities” that prevailed for two months from the end of February.