The Foreigners and Borders Service - SEF (Portuguese: Serviço de Estrangeiros e Fronteiras) was the police service integrated into the Ministry of Internal Affairs, whose mission was to enforce immigration and asylum in Portugal, in accordance with the provisions of constitutional, legal and governmental guidelines.

The Emigration Police were responsible for the control of the land borders and were a division that worked directly under the General Directorate of Public Safety.

In 1928, the Portuguese International Police (Polícia Internacional Portuguesa) were created with the responsibility of monitoring the land borders and foreigners who resided in Portugal.

The PVDE included an International Section which was responsible for verifying the entry, stay and exit of foreigners from the National Territory, their detention if they were deemed undesirable, fighting against espionage, and collaboration with the police of other countries.

35 046 of October 22, the PVDE was transformed into the International and State Defense Police (Polícia Internacional e de Defesa do Estado) (PIDE).

[2] In 2020, 42-year old Ukrainian Ihor Homeniuk was beaten to death while in the SEF's custody at Lisbon Airport; in 2021, three SEF officers – Duarte Laja, Luís Silva and Bruno Sousa – were found guilty of inflicting serious bodily harm that ultimately led to Homeniuk's death and sentenced to several years in jail.