(CNN) -- As soon as refugees fleeing unrest in Libya began flooding over the border into Tunisia, Ali Ben Issi signed up as a volunteer to help them.
Ben Issi, a 20-year-old Tunisian student, works every day at the new transit camp set up by the U.N. refugee agency, helping new arrivals with their passports and paperwork.
He said: "I want to help because the people of Italy are helping Tunisian refugees, so I want to do the same for other people.
"I have two female cousins and several friends also volunteering. There are also many, many people volunteering, giving food, clothes, and even money."
When he has to return to his studies, Ali has promised to continue volunteering at weekends for the International Organization for Migration for as long as is necessary.
Ben Issi is one of an army of Tunisians who have become the backbone of the relief effort to help up to 150,000 people who have crossed the border from Libya to Tunisia in the past week.
Aid organizations say Tunisians living in the area have been handing out food, drinks and clothing to refugees -- even inviting refugees to stay in their homes in a spontaneous show of solidarity.
Teher Cheniti, secretary of the Tunisian Red Crescent, said: "All the families near the frontier have offered their assistance. Many refugee families are living with Tunisians.
"Families are spontaneously cooking and offering hot meals to refugees. On every corner there are people offering meals."
The U.N. refugee agency, the Tunisian government and NGOs have been helping to evacuate as many refugees as they can to their home countries, but they cannot keep up with the average 15,000 a day pouring over the border.
The majority of those crossing the border are Egyptian migrant workers, but the Tunisian Red Crescent said it has dealt with people from 30 different nationalities, including Bangladeshis, Vietnamese and sub-Saharan Africans.
The U.N.'s transit camp has capacity to shelter around 12,000 people, but many others are staying with local families or in public buildings.
Tarek Ben Ali, working at the border in Ras Jdir for the International Organization for Migration Tunisia, said: "I have 12 volunteers under my supervision at the border showing people where they can get water, helping them make phone calls and eventually trying to get them back to their country of origin.
"People from all different levels of society and backgrounds are helping out. They have a big motivation to help. It's part of our culture to give solidarity to people in a bad situation.
"We see many people bringing milk, bread, drinking water and food they have cooked at home.
"In the camp, if anyone doesn't have food or a tent, people are making sure they help them.
"Tunisians are also providing free buses to get people to the airport."
Despite the huge efforts on the ground, aid agencies say the nearest town of Ben Gardane and its surrounding area are at capacity and more international help is needed in evacuating the workers.
Firas Kayal, a spokesman for the U.N. refugee agency on the Tunisian-Libyan border, said: "The situation here remains tense. There is lots of congestion on this side of the border, and we are hearing that many thousands are waiting on the Libyan side to come through.
"The local community has been so generous in providing food, medicines and places to stay, but the capacity of the local community is reaching its limit because the numbers are so huge.
"The local community has been supporting them since the beginning, giving them shelter in schools, public buildings and host families.
"However, we are calling on the international community to help ease the pressure on this little border town to allow more people from the other side of the border to cross."