GHAZNI, Afghanistan (AFP) -- Four security guards were killed in an insurgent attack in southern Afghanistan on Saturday, Afghan authorities said, also claiming to have killed up to 30 rebels amid a surge in violence.

The new violence followed a bloody day for the NATO-led British force which lost eight soldiers in attacks blamed on Taliban insurgents in the country's southern province of Helmand.
The security guards were killed when a supply convoy they were escorting to a NATO-led base came under insurgent rocket attack in the central province of Ghazni, the province's police chief Kheyal Baz Sherzai told AFP.
A day earlier, 11 rebels were killed in an operation by Afghan and international forces elsewhere in Ghazni, provincial governor Mohammad Osman Osmani told AFP separately.
Also on Friday, in the province of Uruzgan in the south, 29 rebels were killed in similar operations, the interior ministry said in the capital, Kabul.
“Bodies of eight of the enemy combatants were left on the battleground,” the ministry said in a statement. The NATO-led International Security Assistance Force (ISAF) helped Afghan police in the operations, it added.
It was impossible to independently verify the reports of these incidents.
Attacks linked to a Taliban-led insurgency have surged in recent weeks with several major offensives under way against Taliban strongholds ahead of the August 20 elections.
Eight British soldiers lost their lives in insurgent strikes on Friday in the southern province of Helmand, where thousands of newly deployed U.S. Marines and British troops are pushing into insurgent areas for the polls.
Britain has now lost 184 troops in Afghanistan since operations began in 2001 -- surpassing the 179 killed in Iraq since the U.S.-led invasion in 2003.