Lebanese Prime Minister Saad al-Hariri has warned that his country is close to "breaking point" due to strains of hosting more than one million Syrian refugees, fearing that unrest could escalate due to tensions between refugees and local communities.

Speaking to foreign media on Friday, Hariri said: "Today, if you go around most of the host communities, there is huge tension between the Lebanese and the Syrians ... I fear civil unrest."

The remarks came as the United Nations refugee agency (UNHCR) said in a report that the number of refugees who have fled the civil war in Syria since it broke out in 2011, now exceeds five million.

Refugees from Syria make up about a quarter of Lebanon's population. They mostly live in informal camps across the country, some, in severe poverty.

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The Lebanese government has long rejected the implementation of formal refugee camps, fearing the permanent presence of refugees.

"Some say we should have refugee camps in Lebanon, I say Lebanon has become a big refugee camp," Hariri said, pointing out that the influx of Syrian refugees in Lebanon has stretched the country's economic resources.

Appeal for aid

The prime minister also said he would appeal for foreign financial support to boost the local economy and improve infrastructure during next week's conference on the post-conflict future of Syria, taking place in the Belgian capital, Brussels.

"I am going ... to make sure that the world understands that Lebanon is on the verge of a breaking point," he said, adding that the country has been "extremely lucky in making sure this crisis has not affected host communities, but we have stretched our luck".

In his bid to increase foreign investment, Hariri's plan to help Lebanon's economic and security situation compels the international community to commit to spending the equivalent of $10,000 to $12,000 a refugee over a span of five to seven years, as opposed to the current level of financial support corresponding to an annual $1,000 to $1,200.

"I think that will make sure that Lebanon is going to stand on its own and the economy will thrive," he said.

The Syrian civil war played a role in weakening the Lebanese economy and has raised tensions among various communities inside Lebanon that support different sides of the conflict. However, there has not been an outburst of violence between Syrian refugees and Lebanese host communities thus far.

Georges Ghali, programmes manager at Lebanese human rights organisation ALEF, said the tensions were rooted in factors including misperceptions whereby the Lebanese believe that refugees were being showered in aid and government policies that had made it difficult for them to obtain official residency.

Lebanese officials, citing World Bank figures, say the cumulative cost of the Syrian conflict to Lebanon was $18.15bn to the end of 2015. Lebanon's annual economic growth has slowed to just over one percent from an average of eight percent, prior to the war, they said.

The government is seeking financial support for a programme of public sector-led investment in infrastructure to boost the economy, and to increase the number of Syrians in education.

Hariri said the plan would "equally benefit Lebanese citizens and displaced Syrians".

To date, the number of documented Syrian refugees in Lebanon is about 1.1 million, according to the latest figures provided by the UNHCR.

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Al Jazeera's Alan Fisher, reporting from Lebanon's Bekaa Valley, said the actual number of Syrian refugees in Lebanon is much higher than the official figure, with more people flowing into the country in the past few weeks.

According to Fisher, most of the new arrivals have not yet registered with the UN, and shortages of food and water are common.

The total number of Syrian refugees abroad amounted to 4.6 million at the end of 2015, but rose to 4.85 million by the end of last year, according to the agency's figures.

The UNHCR estimated another 6.3 million Syrians have been internally displaced.

A UN-led humanitarian appeal to help Syrian refugees and support host communities has received only six percent of the $4.6bn target needed this year.

Palestinian refugees

Lebanon has also been hosting Palestinian refugees since the 1948 Nakba and exodus, which has displaced more than 700,000 people.

Over the years, the number has since drastically increased, especially after the 1967 exodus, which has forced another 300,000 people to flee from Palestine.

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As of 2015, Palestinian refugees remain the largest refugee population in the world, with more than seven million displaced globally. Palestinians in Lebanon and their decedents have since lived in 12 formal refugee camps provided by the UN across the country.

Although figures vary, according to a 2014 report released by UNRWA, there are about 450,000 Palestinian refugees who reside in Lebanon, many of whom live under dire social and economic conditions.