Iranian guards shot dead 10 Afghan migrants illegally trying to cross the border from the western province of Herat, officials in Kabul said Sunday. Thousands of Afghans cross illegally into Iran every year to seek work as Afghanistan's economy struggles to grow amid an Islamist insurgency that erupted after the 2001 fall of the Taliban. "There was a big group, maybe around 200 people, who were trying to cross the border into Iran," Sediq Sediqqi, spokesman for the interior ministry, told AFP about the incident on Friday night. "They were shot at by Iranian border guards. Ten people were killed and 12 others were wounded," he added, confirming they were illegal immigrants. An Iranian embassy spokesman in Kabul was not immediately available to comment. About 2.4 million Afghans -- refugees and illegal immigrants -- live in Iran, many of whom moved after the 1979 Soviet invasion of Afghanistan. In December, Afghan demonstrators tried to storm the Iranian consulate in Herat in protest at the alleged killing of migrants by Iranian security forces. The protesters claimed 13 Afghans who had crossed the border into Iran were seized and later shot dead.