Morocco on Saturday urged Spain to open an investigation into the circumstances of a Western Sahara independence leader"s arrival in the country for medical treatment and explain its findings to Rabat. Madrid should explain "the conditions, circumstances and connivances that led to the fraudulent entry of this person using false documents and a usurped identity," said Foreign Ministry Director General Fouad Yazourh. Spain"s decision to host Polisario Front leader Brahim Ghali without telling Rabat while using what Morocco says are travel documents provided by Algeria and a false name, has angered Rabat, which regards Western Sahara as part of Morocco. The Algeria-backed Polisario seeks the region"s independence and last year said it was resuming an armed struggle that was put on hold by a U.N.-brokered ceasefire in 1991, though there has been little evidence of fighting. In December, the United States recognised Morocco"s claim to Western Sahara in a deal that also included Rabat strengthening its ties with Israel. On Monday, Morocco appeared to relax border controls with the Spanish North African enclave of Ceuta, leading to thousands of people to cross illegally. Rabat later blamed the crossings on the weather and tired border guards though analysts said it appeared to be linked to the diplomatic dispute with Madrid. Ghali faces a court summons in Spain in a war crimes case against him. However, Spain"s High Court has rejected a request by plaintiffs in the case to arrest him. read more Morocco recalled its ambassador to Spain for consultations this week and on Friday she said that relations between the two countries would worsen if Ghali left Spain without a trial.