"I am deeply concerned by the explosive device set off at the British Embassy Zagreb earlier today which injured one member of the security staff. Thankfully his injuries are not too severe," Alexander said in New York.
"The security of our staff is of paramount importance to the FCO. We do not know who planted the explosive device and cannot speculate at this time. We will work closely with the Croatian authorities as they seek to identify and prosecute those responsible. We are grateful for their prompt response to the incident this morning," Alexander said.
The statement further quoted the minister as saying that public access to the British Embassy and Consulate in Zagreb was suspended on Monday, but that full services would resume on Tuesday.
Alexander also said that Britain was keeping travel advice for its citizens under active review.