Iran says it is "concerned" about a U.S.-Afghan strategic partnershipagreement signed earlier this week that could keep an American military presence in Afghanistan for years to come.

Foreign Ministry spokesman Ramin Mehmanparast says the pact will increase instability in Afghanistan, which borders Iran to the east.

He says a withdrawal of foreign troops is the best way to bring security. His comments were reported by the official IRNA news agency Sunday. AP