Kabul, Afghanistan ? Hundreds of people linked to a hard-line Islamic group have been arrested in Kabul in connection with an alleged plot to overthrow the government of interim Prime Minister Hamid Karzai and attack foreigners, Afghan officials said Thursday.

The plot, the most serious threat yet to Karzai’s fledgling administration, included plans to set off bombs throughout the capital, said Gen. Din Muhammad Jurat, the director general for security at the Interior Ministry. He said most of those arrested were members of Hezb-e-Islami, a hard-line Islamic group headed by former prime minister Gulbuddin Hekmatyar.

“They wanted to launch a coup d’etat against the government,” said Mohammed Naseer, the security director at the Kabul governor’s office. He said the suspects also wanted to disrupt the loya jirga, a political gathering planned for June to select a new Afghan government.

Interior Minister Yunus Qanooni said the goal of the plotters was still under investigation, but that the suspects were engaged in the planning of “terrorism, abductions and sabotage.” He said authorities had seized explosives and remote control devices and found “written documents indicating that they would carry out these acts.” He did not elaborate

When asked if the plotters planned to assassinate Karzai, Qanooni said: “There were a series of attacks planned against a number of prominent Afghan individuals, including Chairman Karzai and the former king,” Mohammad Zaher Shah, who is due to return to Afghanistan from Italy later this month. Qanooni added that authorities had evidence the men planned to attack foreigners.

The roundups could heighten tensions between Pashtuns, Afghanistan’s largest ethnic group, and the northern alliance, which is dominated by ethnic Tajiks and which controls the interior and other key ministries. Hekmatyar’s following is largely Pashtun, and Pashtun leaders may interpret the arrests as an attempt to stifle their moves toward Pashtun unity in advance of the loya jirga.

When asked if most of those arrested were Pashtuns, Qanooni said only: “Let’s not turn it into an ethnic issue.”

Qanooni said more than 300 people had been arrested, and that 160 were still being held Thursday. A Western official in Kabul, speaking on condition of anonymity, said only 10 of those detained were being held on suspicion of serious offenses, including terrorism.

Lt. Col. Neal Peckham, a spokesman for the International Security Assistance Force peacekeepers, said weapons had been found and that those arrested also included Pakistani members of another militant group, the Jamaat-e-Islami, a Pakistan Islamic organization with close ties to Hekmatyar. He said the peacekeepers were not involved in the operations, but had been tipped off beforehand.

Afghan police on Monday raided the home of Hekmatyar’s one-time aide, Wahidullah Sabaoon, but there was some confusion Thursday over his whereabouts. Jurat and Naseer said Sabaoon was among those arrested in the sweep, but Peckham said the man was still at large.

Sabaoon was once the military chief of Hezb-e-Islami and served as Afghanistan’s defense minister in 1995 when Hekmatyar became prime minister under President Burhanuddin Rabbani. When the Taliban took over the country in 1996, Sabaoon allied himself with the northern alliance resistance, becoming the finance minister for the goverment-in-exile.

Hekmatyar has been a vocal opponent of Karzai and of U.S. presence on Afghan soil, but last month his deputy, Jumma Khan Hamdard, said the party was ready to cooperate with the interim administration.

A senior leader of Hezb-e-Islami, Qutbuddin Hilal, said those arrested were former members of the group.

“There is no truth in these reports that our men are being arrested,” Hilal said.

Ruthless power struggles among Hekmatyar’s forces and northern alliance factions devastated much of Kabul during the early 1990s, with 50,000 people, mostly civilians, killed, according to the International Red Cross.

Hekmatyar fled to Iran after the Taliban took the capital in 1996, although the Iranian government recently closed his offices in Tehran and his whereabouts are unknown.

Naseer said the men arrested “were linked to both al-Qaida and Gulbuddin Hekmatyar,” but he refused to elaborate. He said most of those arrested were living in the upscale Wazir Akhbar Khan and Old Makrorayan neighborhoods of central Kabul.

Jurat said the interim administration had documents and strong evidence that linked Hekmatyar to the plot, but made no mention of al-Qaida, Osama bin Laden’s terrorist network.