Kosovo's state prosecutor has said seven Islamic State group suspects detained last week were planning attacks in the Balkans and were receiving instructions from militants in Syria.

Anti-terror police arrested seven men in three different towns on Friday and the group was subsequently jailed for 30 days pending further investigation by the court of first instance in Pristina.

The seven men had contacts in neighbouring countries such as Macedonia and Albania, and other suspects from the group still remain at large, a document from the state prosecutor seen by Reuters showed.

Kosovo has not seen any militant attacks on its home turf, but at least 200 people have been detained or investigated for alleged Islamic State-related offences.

Around 300 Kosovars have gone to fight with the group in Syria and Iraq.

According to the prosecution, the seven men were in contact with an Islamic State member, the self-declared "commander of Albanians in Syria and Iraq", Lavdrim Muhaxheri, during September and October this year when he gave them instructions on attacks.

"They have prepared terrorist attacks on the territory of the Balkans, but first in Kosovo. They have planned to attack different buildings including security institutions," the prosecution said.

The men wanted to create a regional offshoot of Islamic State, and one had already spent time fighting alongside the group in Syria, the document said.

Domestic and regional security agencies in Kosovo, including NATO and the EU police mission, are worried those returning from combat zones could pose a threat to security, but so far there have been no attacks in Kosovo.

The prosecution has yet to file charges against the group.

Nasuf Hasani, the lawyer of one defendant, said he would appeal the court's decision to jail his client.

Most of Kosovo's ethnic Albanian majority are nominally Muslim but overwhelmingly secular.

Kosovo declared independence from Serbia in 2008 with the backing of the West.

In 2015 it adopted a law introducing jail sentences of up to 15 years for anyone found guilty of fighting in wars abroad.