Four illegal immigrants trying to slip into Greece through the Evros area of Thrace were killed by landmines early yesterday on the Greek side of the border in the worst incident of its sort since late 1999 when five Iraqi Kurds died in one minefield. Another three members of the same party were badly injured, and one was hospitalized in critical condition in Alexandroupolis. All the dead and injured were Iraqi Kurds, but their names had not been ascertained by late yesterday. The group of seven had crossed from Turkey over the frozen Evros River, and entered Greece just before 7 a.m. in the area of Gemisti, near the village of Ferres. Shortly afterwards, they entered a marked, fenced minefield where exploding mines instantly killed four. An army mine-clearing unit pulled out the dead and wounded. At least 13 immigrants have died in Evros minefields over the past two years. Although Greece and Turkey agreed in April to endorse the 1997 Ottawa convention against landmines, this has yet to have been translated into action on their shared border.