U.S. troops and warplanes attacked Taliban (search) rebels besieging a remote checkpoint in southern Afghanistan, an Afghan official said Saturday. Eight militants were killed.

American forces also skirmished with guerrillas who attacked them with rockets near the country's eastern border, the U.S. military said, part of an insurgency threatening plans for landmark national elections in September.

The battle for the checkpoint was in Daychopan district of Zabul (search) province, about 200 miles southwest of the capital Kabul, provincial military commander Naimatullah Khan said.

Khan said Afghan troops used a satellite phone to call for help when a band of 200 Taliban crept down from the mountains and opened fire on the checkpoint in an area called Hazar Boosth (search).

"Coalition planes bombed the area, and after a four-hour gunfight, the Taliban pulled back into the mountains," Khan said. "Eight of them were killed. We've gathered up their bodies and guns."

U.S. military spokesman Lt. Col. Tucker Mansager confirmed that a group of Marines backed by warplanes had clashed Friday evening with a "fairly substantial number of militants."

He had no word on any casualties or details of the fighting.

Meanwhile, militants fired two rockets and fired on U.S.-led forces near Nangarlam in eastern Kunar (search) province Thursday, Mansager said. Warplanes came to their aid, ending the engagement.

No Americans were hurt and there was no information on enemy casualties.

In another incident, gunmen opened fire on a car carrying a government official in Uruzgan province, wounding him seriously and killing three of his guards, police said.

Mullah Abdul Ghali, the deputy mayor of Girishk in Helmand (search) province, was riding through his hometown, Deh Rawood, when the attackers struck.

Three more soldiers guarding Ghali were also injured, Girishk police chief Haji Bir Jan said. He said the assailants, who escaped, were Taliban.

News of the latest fighting comes after the U.S. military said another fierce battle killed 17 militants in the mountains of southern Afghanistan on Thursday, the bloodiest clash in almost a year. Three Marines were slightly wounded.

It also follows the slaying of five aid workers, including three foreigners, on Wednesday in a previously peaceful northern region, the deadliest assault on international relief agencies since U.S. forces drove the Taliban from power in late 2001.

Violence across Afghanistan has killed more than 400 people this year, including election workers and foreign troops as well as dozens of Afghan soldiers, casting doubt on the country's readiness for national elections slate for September.

The United Nations has registered about 3 million voters so far, or about one-third of the Afghans eligible. But it has yet to venture into remote districts of the south and east because of poor security.