Details of the service members' identities and the exact location of Saturday's blasts were not immediately disclosed.
Five service members with the international coalition have been killed so far in February, and 36 since the start of the year. Last year was the deadliest of the nearly decade-long war for international troops, with more than 700 killed, compared to just more than 500 in 2009, previously the worst of the war.
The U.S. plans to start withdrawing troops from Afghanistan in July with the aim of handing over responsibility for the country's security to Afghan forces. NATO aims to pull all its troops out by 2014.