The number of refugees fleeing the bloodshed in Syria could reach 700,000 by the end of the year, the United Nations has warned.More than 294,000 refugees have already crossed into the neighbouring countries of Jordan, Iraq, Lebanon and Turkey since the conflict began 18 months ago.
The UN refugee agency said more money was urgently needed to care for the hundreds of thousands expected to arrive in camps over the next three months.
"We are running out of time," Panos Moumtzsis, the UN chief co-ordinator for Syrian refugees, told reporters in Geneva.
He said humanitarian agencies need £305m (\$487.9m) to fund their operations until the end of the year. At present, only £88m is available - just 29% of the total needed.
With winter approaching, he said money was urgently required for tents, clothing, blankets and heaters.
Riots erupted this week at the UN-run Zaatari refugee camp in northern Jordan after Syrians complained about poor living conditions at the 30,000-strong compound.
Police used tear gas to quell the violence and eight Syrians were charged with "unlawful assembly and carrying out riots".
More than 20 officers were injured in similar disturbances at the camp last month.
Jordan has complained of limited resources to cope with the growing number of Syrians flooding into the country.
More than 305 people were killed across Syria on Wednesday, making it the bloodiest day of the 18-month revolt, according to the UK-based Syrian Observatory for Human Rights.
Fourteen people were killed when two bombs rocked the headquarters of the armed forces general staff in the heart of Damascus.
An Islamist rebel group said it carried out the attack, and five of its fighters, including a suicide bomber, died during the assault.
The Syrian Observatory says more than 30,000 people have been killed since the uprising against President Bashar al Assad began in March last year.