In 1901, there were several massacres of Serbs in the Kosovo Vilayet, carried out by Albanians. Serbs were maltreated and accused of being Serbian agents. Panic ensued, and Serbs, primarily from the border areas fled to Serbia. The Porte did not suppress the Albanian movement nor protect the Serbs. Albanians who participated in the Greco-Turkish War (1897) used weapons not turned in to the authorities against the Serbs in Old Serbia. In May 1901, Albanians set Sjenica, Novi Pazar and Pristina on fire. The Albanians went on a rampage massacring Serbs in Pristina. Ibarski Kolašin (now known as North Kosovo), a forested region made up of 40 villages, largely inhabited by Serbs, where Serbian teachers and priests were active, had long irritated the Albanians and Ottoman government; Serbs were continuously maltreated in the region. The Serbian government observed the developments in Kolašin, and did not remain idle. The situation became serious, with Serbs being smuggled arms by Serbia to defend themselves. Albanian atrocities had taken such wide proportions that the government of Vladan Đorđević was forced to begin a wide diplomatical action for the protection Serbs in Old Serbia; when these efforts did not take fruit, and the Albanians were empowered and intensified atrocities against the Serbs, the unprotected Kosovo Serbs began to demand arms to protect themselves. The Ottoman government was made aware of the smuggling, that most arms ended up in Kolašin, by Isa Boletini in early July, Boletini having led the investigation. In the summer of 1901, after the Ottoman investigation, Albanians massacred Serbs in the Kolašin area. Boletini was present while the organised atrocities on Kolašin were carried out, including massacres, rape, blackmail, looting and eviction of local ethnic Serbs. The atrocities prompted the Russian government to intervene at the Porte. Violence in Kolašin stopped, however, Albanian atrocities in other regions continued. Russia demanded that the Albanians and Turkish gendarmeries be punished and the Serbs be allowed to keep the arms for protection. Austria-Hungary, who supported the Albanians, tried to downplay the massacre. The Porte answered by mass arrests and criminalizing the Albanian language. The governor (vali) was dismissed, and several other anti-Serb officials, and Albanian chieftains who had been especially cruel, were removed from their posts.
The events were instrumental in the "Kolašin affair" (Serbian Cyrillic: Колашинска афера), a diplomatic conflict between Austria-Hungary, which supported the Albanians, and Serbia, which was supported by Russia. With time, the diplomatic conflict grew into an open confrontation between the two sides.