* Shootings of migrants on Egypt-Israel border on rise
* Upsurge indicates shifting African migration patterns
CAIRO, July 30 (Reuters) - Egypt has stepped up shootings of African migrants trying to slip across its border into Israel in a sign that shifts in migration elsewhere in Africa may be pushing more migrants to brave the trek to the Jewish state.
Egyptian police have shot dead at least six African migrants at the Egypt-Israel frontier since May, ending a 6-month lull as police responded to what security sources said was an increased flow of human traffic through Egypt.
The renewed violence is a leading indicator of likely shifts in an African migration trail with origins south of Egypt as rising numbers of migrants stream out of Eritrea on the one hand, and an alternate smuggling route to Italy via Libya gets tougher.
It is also a sign of the unexpected potential consequences of policies intended to block illegal migration to Europe, where immigration is a hot political issue especially at a time of global economic crisis.
"The numbers (at the Egypt-Israel border) are increasing. That route is being used again more heavily than before," said Gasser Abdel Razek, Egypt country director of refugee legal aid group AMERA.
Aid workers describe the migration route through Egypt as a river with two branches starting in the Horn of Africa and catering to economic migrants and refugees, some fleeing Eritrean authoritarianism or ethnic strife in Sudan's Darfur.
The route splits in Sudan, where would-be migrants typically take a chance on one of two impossible choices -- to brave gunfire at the Egyptian border on the way to Israel, or risk drowning on a rickety boat to Europe from Libya.
"I heard it (Libya) is becoming difficult for them ... I am hearing there is strong monitoring along this route, on the border between Libya and Sudan," said Mohamed Dualeh, head of an office of the U.N. refugee agency in Kassala in east Sudan, through which many migrants transit, especially Eritreans.
"If you are a human being, and you cannot go because one route is blocked, you look for another route," he said.
Added to the mix, UNHCR says the migrant flow out of the Horn of Africa state of Eritrea to Sudan has doubled in the first half of 2009 to 11,000 new arrivals. Eritreans are the largest group of migrants attempting to cross into Israel.
Egypt fears the unfettered flow of migrants at its strategic Sinai border could pose a security threat in an area where it already fears inroads by Islamist militants who sometimes find refuge in remote craggy mountains.
Egypt also faces Israeli pressure to halt the migrant flow.
For several years until 2008, the route to Israel via Egypt was increasingly popular as it was seen as a safer choice than risking passage by sea from Libya to Europe -- a more popular migrant destination. But passage continued on both routes.
Then, the calculation changed, and the Egypt route dried up.
Migrants were scared off by a surge of shootings last year at the Egypt-Israel border that killed at least 28 migrants.
Cairo, which had for years tolerated tens of thousands of African migrants on its territory, also deported hundreds of Eritrean asylum seekers back to Asmara despite objections from the United Nations, which feared they could face torture.
Migrants were spooked further in January when a number of refugees headed for Israel died in an airstrike on a suspected Egypt-bound arms convoy with which they were travelling, a lawyer who recently worked in refugee camps in Sudan said.
As a result, he said, migrants gravitated heavily to the Libya route. "Many of them have relatives and friends who died on the (Egypt) border," the lawyer said, asking not to be named due to the sensitivity of the organisation for which he worked.
But several months into a noticeable quiet on the Egyptian frontier, Libya ratified a deal with Italy to quell migrant flows to Europe. In May, Italy began deporting migrant boats intercepted at sea back to Libya.
In Sudan, a transit hub for migrants hoping to hook up with smugglers, migrants from the Horn of Africa say their perception is that the route to Libya was now closed, if only temporarily.
"In May and June there was an almost total blockade on departures (from Libya), and the number of boat departures in Libya fell really dramatically ... They are still not getting through very much," said Bill Frelick, refugee policy director at Human Rights Watch, which is monitoring the situation.
Human Rights Watch says hundreds of migrants have been returned to Libya after being intercepted at sea under the policy, and face indefinite detention and possible mistreatment.
Simultaneously, Egyptian police noticed a surge in African migrants trying to slip into Israel and resumed shooting to quell the flow. Fresh arrests are reported almost daily.
Monthly migrant arrests by Egypt at the border have surged, rising five-fold in May to 55 and then doubling again to 114 in June and 160 in July, security sources said. That compares to just six arrests in January.
Egyptian security sources say they believe the rising detentions reflect an actual increase in migrant numbers, and are not simply a result of more police work at the border.
That comes as hazards for migrants look to get tougher. Human Rights Watch says Italy has also pledged to help build a radar system to monitor Libya's desert borders, a main entry point for African migrants. (Additional reporting by Yusri Mohamed in Ismailia and Andrew Heavens in Khartoum; Editing by Samia Nakhoul )
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