At least five people were killed and about 30 wounded after twin bomb blasts struck the Afghan city of Herat.
The fatalities occurred after a roadside bomb in the city centre.
In the second assault, a suicide bomber attacked the Nato-led Provincial Reconstruction Team (PRT) base on the outskirts of the city.
Meanwhile, an Afghan soldier shot dead a Nato soldier in the province of Uruzgan, the latest in a string of attacks by "rogue" security personnel.
A local commander told the BBC that the soldier had fled the camp after the incident. A Nato spokesman said the alliance was investigating the exact circumstances of the attack.
The BBC's Bilal Sarwary in Kabul says that such attacks by rogue Afghan soldiers and Taliban infiltrators are yet another challenge to Nato's already perilous mission in Afghanistan.
Afghan officials say such attacks have shattered the confidence of Afghan security institutions and create mistrust between the Afghan and international forces.
The Taliban recently declared a "spring offensive" of attacks in Afghanistan. There have been regular attacks on city centres and high-profile killings of key figures in the Afghan security forces over the past month.
On Sunday, Taliban militants attacked a construction firm in the province of Logar, killing four road workers, a provincial spokesman told the BBC.
Herat - a relatively peaceful city - is one of the places due to be handed over to Afghan control in July when international forces begin their phased withdrawal.
An Afghan intelligence official there said that the first attack was a "powerful" bomb blast.
"It happened at a busy place at a busy time. The windows of nearby buildings were broken. I was nearby when the explosion took place," he told the BBC.
Witnesses at the scene of the PRT base said at least two suicide bombers attacked the compound, while a number of insurgents tried to get inside.
Attackers are also said to have taken up positions on a nearby buildings to shoot into the compound. Nato called in helicopters for defence.
A police official told the BBC that shops had been closed and that police and army officers had been deployed across the city.
PRTs are typically joint military and civilian operations designed to help build up Afghan government capacity in a province. There are 28 of them across Afghanistan.
Earlier, Nato generals in Afghanistan apologised after civilians were killed in an air strike on Sunday. Afghan President Hamid Karzai had criticised the coalition for the attack, which killed nine people.