Last year, more than 8,000 people were killed in insurgency-related attacks, the most since the 2001 US-led invasion, and violence has claimed more than 1,700 lives so far this year.
Marvin Weinbaum, a former State Department official and now an Afghanistan analyst at the Washington-based Middle East Institute, said rising casualties would sharpen the Afghanistan focus in the US presidential race.
"What's being brought home is the nature of the conflict. It's in the true fashion of a guerrilla operation and we're not prepared for it," Weinbaum said.
In yesterday deadliest attack, a roadside bomb hit a coalition convoy west of the main southern city of Kandahar, killing four troops and wounding two others.
Lieutenant Colonel Paul Fanning, a coalition spokesman, said gunmen opened fire on the damaged vehicles and three Afghans also were hurt. He declined to release the nationality of the troops, who were involved in training Afghan forces.
To the east, a Polish soldier from the separate NATO-led force died when a bomb hit his patrol after midnight in Paktika province. Jacek Poplawski, a Polish military spokesman in Warsaw, said four other soldiers were wounded.
In separate events, attackers detonated bombs and opened fire on vehicles carrying Afghan troops in Zabul and Kunar provinces, killing five soldiers and wounding three.
A suspected Taliban rocket hit a hospital in the northeastern town of Asadabad close to the Pakistan border, killing one man and wounding another man and a woman, Reuters reported, quoting provincial Governor Sayed Fazlullah Wahidi.
He said the rocket appeared to have been fired from across the border inside Pakistan. Afghan officials often accuse Pakistan of aiding Taliban and Al Qaeda militants who launch cross-border attacks into Afghanistan, charges Pakistan denies.
Yesterday's attacks capped a bloody week. NATO and Afghan troops backed by warplanes on Wednesday attacked up to 400 Taliban militants who had seized the strategic Arghandab valley, within striking distance of Kandahar.
