Israel said that the Islamic State group had been planning attacks "in the Balkans" and specifically warned its citizens not to attend an upcoming Israel-Albania football match.
"In recent days, persons linked to Islamic State have been arrested in the Balkans," a Hebrew-language statement from Prime Minister Benjamin Netanyahu's office said.
"Those arrested, and others linked to them, planned to carry out a number of attacks against a range of targets in the Balkans, including a game scheduled between Albania and Israel for November 12."
The Albanian national football federation said in a statement Saturday's match would now be held in the central town of Elbasan instead of the northern town of Shkodra as originally planned.
But Israel said its fans should nevertheless stay away.
"Despite the arrests, and in accordance with a situation report, there is still a significant risk of attacks in the area," the government statement said.
"Therefore the counter terrorism bureau is publishing a warning against travel to Albania, in light of a high concrete risk, and advises Israelis not to attend the team's game due to take place on November 12." Police in Albania detained four people on Saturday on suspicion of financing terrorism, recruiting IS fighters for Syria and spreading "terrorist propaganda".
The state prosecutor in Tirana refused to confirm a report in the local Panorama newspaper of plans for a terror strike during the match.
According to the Panorama report, the four suspects, including a doctor and hairdresser from Shkodra, were planning to obtain explosives for attacks before and during Saturday's match.
The prosecutor's office said that the suspects had regularly visited a radical mosque in a Tirana suburb, which was closed last year, and recently attended the trial of a group of radical imams accused of advocating terrorism.
They were arrested in a crackdown that also led to the detention of nine people in neighbouring Kosovo.
In Pristina, a source in the prosecutor's office told AFP on Tuesday that the group planned "attacks on institutions and vital buildings in Kosovo", adding that they had "no information" on a planned attack in Albania.
Albania, home to around three million people, is a predominantly Muslim country where the vast majority practise a moderate form of Islam. But radical fringes have been on the rise in recent years following the wars in Syria and Iraq.
From 2012 to 2014, between 100 and 120 Albanians joined the ranks of jihadists abroad, according to authorities.
About 15 Albanians have been killed in Syria or Iraq, and around 30 have returned home.