The policemen were travelling in a four-wheel drive vehicle in the Maruf district of Kandahar province, Khan Muhammad said.
"Seven police officers of Kandahar city driving in a four-wheel drive vehicle were killed by a remote controlled mine today," said Khan, who is the provincial police chief.
In another sign of spiralling violence ahead of the 9 October elections, Khan said two suspected Taliban fighters were killed by their own bomb on Tuesday evening.
"Two Taliban who were attempting to plant a bomb close to the house of the Kandahar police criminal investigation director were killed when their bomb went off and killed them," he said.
In the southeast province of Khost, three Afghan electoral workers were injured in an attack on Monday by suspected Taliban, who have vowed to disrupt the polls saying they serve US interests.
"In an ambush by Taliban three electoral workers were injured near Jaji Maidan district," military commander Khayal Baz Khan said.
Twelve electoral workers were among hundreds of people killed in anti-government violence this year, and more than 30 electoral staff have been injured.
Khan also blamed Taliban fighters for a rocket attack in the village of Tira in Khost where a girl was killed and three others injured.
Car bomb discovered
In the capital Kabul, a powerful bomb was discovered and defused near a military camp, a spokesman for the Nato-led peacekeeping force said.
The Taliban are blamed for most
of the attacks in Afghanistan
The 100 pound (45kg) bomb was found within two kilometres of Camp Julien, used by Canadian troops, and defused in the early hours of Tuesday morning.
In central Uruzgan province, Afghan security forces killed seven suspected Taliban fighters during a two-hour battle after they ambushed a battalion of government troops some 40km (24 miles) east of the provincial capital Tirin Kot.
"Seven Taliban were killed during the fighting which lasted for two hours," provincial administrative chief Fazil Rabi said.
The fighting erupted Monday after more than 100 Taliban fighters attacked troops with small arms and machine guns in district of Khas Uruzgan.
"More than 100 Taliban attacked our troops. We killed seven of them," Rabi said.
The troops pursued the rebels in the mountains throughout the night, with US military helicopters providing air support, Rabi said.
In a separate incident on Sunday US-led soldiers captured 16 alleged fighters after a day of fighting near the southeast border town of Spin Boldak.
Six of the insurgents were injured in the fighting, but the US-led coalition said there were no injuries among its forces.
More than 18,000 US-led troops are in Afghanistan pursuing Taliban and al-Qaida fighters across the southern and eastern provinces.
HRW says the situation in
Afghanistan has not changed
The Taliban and some tribal commanders believe the US has invaded Afghanistan and imposed its will on the people. They accuse interim president Hamid Karzai of being a US-puppet whose government's rigging of elections will ensure him an easy victory in upcoming elections.
Analysts and rights groups like Human Rights Watch have warned that political and economic conditions in Afghanistan havechanged since the Taliban were ousted.
They have also cast a shadow of doubt on how free and fair the elections are going to be amid allegations of coercion by the interim government.