(Muhammad Hamed/Reuters)

More than 3 million people have sought refuge from the fighting in Syria, the United Nations' refugee agency announced today.

That means the Syrian crisis, which has persisted since a civilian uprising began in 2011, is the biggest refugee operation in the UNHCR's 64-year history, the agency said.

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Antonio Guterres, the U.N. high commissioner for refugees, said the international effort to help Syrian refugees was insufficient to meet their growing needs and number.

"The world is failing to meet the needs of [Syrian] refugees and the countries hosting them," Guterres said, adding that, while the response to the crisis has been generous, "the bitter truth is that it falls far short of what's needed."

In addition to the 3 million people who have sought shelter in neighboring countries, including Lebanon, Jordan and Turkey, another 6.5 million refugees have been displaced within Syria, the agency said, adding that half of those people were children. The UNHCR concluded that almost half of the Syrian civilian population has had to leave its homes.

Not only are the refugees fleeing violence, but because they frequently bounce from village to village before finally leaving their home country, they arrive in neighboring countries in increasingly "shocking states[s]," according to a UNHCR statement.

"There are worrying signs too that the journey out of Syria is becoming tougher, with many people forced to pay bribes at armed checkpoints proliferating along the borders," the statement said.

Long-term medical conditions, steep food and commodity prices and unemployment are also problems that Syrians are plagued with once they escape the areas of greatest danger, the UNHCR added.