LISBON (Reuters) - The head of Portugal’s SEF border service resigned on Wednesday after months of backlash over the fatal beating of a Ukrainian man detained at Lisbon airport for trying to enter the country without a valid visa. Ihor Homenyuk, 40, died in March at an airport detention centre run by SEF where he was taken after refusing to board a flight out of the country. Three immigration officers accused of beating up Homenyuk with an expandable baton after the man became “agitated” over his detention have been charged with murder, prosecutors said in September. The death raised an outcry that resurfaced on Monday over unconfirmed reports that SEF planned to install panic buttons in detention facilities, which human rights activists said was an inadequate response to the incident. The interior ministry, which oversees SEF, said agency chief Cristina Gatoes resigned as part of a restructuring plan to more clearly separate police and administrative functions in dealing with immigrants and travellers. The ministry declined further comment on the resignation, and the SEF did not immediately respond to a Reuters question on whether it was linked to the Ukrainian man’s death. “After learning the circumstances of the Ukrainian citizen’s death at Lisbon Airport, resignation was the only possible action,” opposition PSD lawmaker Ricardo Leite wrote on Twitter, referring to Gatoes’ departure. “The resignation is a first, delayed step - but unless it is accompanied by structural changes as promised by the interior minister in March, it is insufficient,” said Ana Logrado, spokeswoman for the Humans Before Borders rights group. “The crime committed against the Ukrainian citizen was not an isolated event,” Amnesty International’s Portuguese branch chief Pedro Neto said, adding there had been other incidents of abuse against foreigners arriving in Portugal, and that more investment in training of border officers was needed.