An explosive device thrown into a compound damaged four vehicles belonging to the International Committee of the Red Cross (ICRC) in northwest Pakistan on Saturday, but there were no casualties.
"Early in the morning something was thrown inside the ICRC compound in Peshawar and damaged four vehicles and some property, but caused no injuries or fatalities," ICRC spokesman Raza Hamdani told the agency.
The ICRC has suspended field operations in Peshawar pending a security review while police investigate.
This is the second attack on a foreign aid agency in North West Frontier Province this week.
On Monday, a grenade was thrown at a compound of the US Save the Children aid group in Battagram, wounding two Pakistani employees.
Foreign aid groups, helping communities recovering from a devastating earthquake in late 2005, say they have been threatened by hardline Islamist groups opposed to their work with women.