Armed rangers in South Africa's Kruger National Park have killed nearly 500 poachers from neighboring Mozambique in the past five years, according to Mozambique's former president Joaquim Chissano.

Kruger, the largest game reserve in Africa, is on the front lines of a surge in rhino poaching. The demand for rhino horn has risen in recent years in Asia, where it is a coveted ingredient in traditional medicine. Kruger shares a porous 210-mile border with Mozambique, and its rangers have the authority to open fire on armed poaching gangs if they are threatened with lethal force.

A spokesman at Kruger said data was not available on the number of poaching-related arrests made in the past year, although the national parks agency says most poachers who are arrested are from Mozambique. South African police could not confirm the number of the poachers killed by Monday.

Chissano, who has a foundation involved in wildlife conservation, said 82 Mozambican poachers had been killed in Kruger Park so far this year, compared with 106 during the whole of 2014. He did not cite where he got those figures.

"It worries me that quite a large number of Mozambicans killed in Kruger Park in poaching activities," the former president said. "Each of these Mozambicans dead means more poverty for his family, because they can no longer count on him to fight for better living conditions."

Mozambique is one of the world's poorest countries, which drives some of its citizens to resort to poaching in Kruger. There are also many South African villages near the border that have been involved in poaching and thrive on the income from the illegal trade.

Poaching is also common inside Mozambique. Poaching gangs have killed about half of the country's elephants, with the species population declining from 20,000 to 10,300 in recent years, according to the Wildlife Conservation Society, a US environmental group.

According to a 2014 report by the UN and Interpol, 1,000 rhinos were poached last year, an alarming increase from only 50 in 2007. The report points out how the underground poaching trade is extremely lucrative and funds many criminal and terrorist organizations around the world.

Mozambique approved a new law last June that introduced tougher penalties against convicted poachers, including heavy fines and prison sentences of up to 12 years. Before the new law, poaching was considered a misdemeanor crime in Mozambique without serious consequences.