While we were sleeping

Photographer Juan Medina has been documenting the arrival of African migrants at the Spanish island of Fuerteventura since 1999 a phenomenon he describes as one of the most horrific, cruel and important immigration movements of our time.

The migration is based on the fact that If you set sail at dusk from the coast of Western Sahara in a small boat, it is possible that by morning you would reach the lighthouse at Fuerteventura, the closest of the Canary Islands to Africa. More than 7,000 immigrants, mostly from sub-Saharan Africa but also from such distant locations as Kashmir - attempted this desperate Atlantic passage in 2003, and the numbers show no signs of diminishing.

For most immigrants, the Canary Islands are not their final destination, but rather the first obstacle they need to overcome en route to other, bigger, richer European cities. Those who survive the dangerous voyage are served with expulsion forms as they arrive, and charged with illegal entry. Yet many do not ever set foot on Spanish shores; their overcrowded handmade boats no match for the powerful Atlantic currents.

Barely a week passes without a report of a boat carrying immigrants smashed on the rocks, its occupants drowned, lost at sea or washed up on the beach. Bodies recovered by the Guardia Civil are buried in cemeteries closest to the spot where they were found. Such deaths are commemorated by a numbered plaque. Unsurprisingly, three of the most haunting pictures of drowned would-be immigrants.

Juan Medina tells the desperate story of this human tragedy. Working at night and in the cold light of morning his striking and unflinching photographs uncover the unseen life and death struggle of immigrants as they attempt the perilous journey to a better life in Europe.

Medina works for Reuters and his pictures at the Host Gallery in London is accompanied by a digital presentation of Reuters wider coverage of immigration to Spain.

This exhibition is shown with another, Weegee Photographs 1935-1960. Weegee (real name Arthur Fellig) specialised in crime scene pictures. He also captured the personal stories of the citys immigrant and working class communities.

The two sets of photographs are separated by decades but Weegee and Medina are able to make the anonymous personal. The lives and deaths recorded in their pictures might never have been acknowledged were it not for the photographers desire as journalists to imbue the rougher side of life with a significance otherwise denied.

Both shows display brutal uncensored events but the presentation of them as a whole enriches each story beyond the merely sensational, causing the viewer to stop, think and wonder about what happened while we were sleeping.

* Host Gallery, I Honduras Street, London EC1Y OTH; tel 0207 253 2770