A Pakistani diplomat is alleged to have committed a domestic rape while under the protection of diplomatic immunity, the Foreign Office said.
Mark Simmonds noted the alleged offence in the annual report on serious offences alleged against foreign diplomats and emphasised the Foreign Office seeks to have immunity waived in serious cases.
The Foreign Office defines serious offences as those which would carry a sentence of more than 12 months if a conviction was secured.
The rape allegation was among 14 offences alleged against foreign diplomats, which also included a child abduction by a Pakistani diplomat, claims of actual bodily harm against a Cameroon and a Zambian diplomat, and a sexual assault alleged against a Zambian diplomat.
There were six drink-driving claims made - two against Saudi diplomats and one each against officials from Belarus, Macedonia, Kuwait and Zambia.
In a written statement to MPs, Mr Simmonds said: "Some 21,500 people are entitled to diplomatic immunity in the United Kingdom and the majority of diplomats abide by UK law. The number of alleged serious crimes committed by members of the diplomatic community in the UK is proportionately low.
"Under the Vienna Convention on Diplomatic Relations 1961, those entitled to immunity are expected to obey the law. The FCO does not tolerate foreign diplomats breaking the law.
"We take all allegations of illegal activity seriously. When instances of alleged criminal conduct are brought to our attention by the police, we ask the relevant foreign government to waive diplomatic immunity where appropriate.
"For the most serious offences, and when a relevant waiver has not been granted, we seek the immediate withdrawal of the diplomat."
Amongst the other allegations was one count of driving a vehicle reported as lost or stolen and without insurance, against a Sierra Leone official, one of driving whilst under the influence of alcohol and without insurance, against a diplomat from El Salvador, and one public order offence claimed against a diplomat from Kuwait.