ALGIERS (Reuters) - The United Nations said on Thursday it feared for the safety of Syrians barred from entering Algeria from the south, saying some of those turned back were refugees left stranded in the desert and not suspected militants as Algiers maintains.

The official overseeing migrant policy at Algeria’s interior ministry said on Wednesday that Syrians who had arrived overland from the south recently were members of defeated militant groups from Syria’s civil war who would pose a security threat.

But the U.N. High Commissioner for Refugees criticized the decision, saying that some of the Syrians mentioned by the Algerian official were known to be registered refugees.

“(They) have fled conflict and persecution or claim to have attempted to seek international protection in Algeria,” a UNHCR statement said.”According to information made available to UNHCR, 20 individuals from this group currently remain stranded in the desert, three kilometers from the Guezzam border post where they are exposed to the elements. The other 100 individuals who were taken to the border are unaccounted for,” the statement said.

Citing an “urgent humanitarian imperative”, UNHCR said it had appealed to Algerian authorities for access to Syrians affected by the ban to identify those in need of international protection and ensure their safety.

Hassen Kacimi, the interior ministry officials, said around 100 Syrians had reached the southern border with the help of local armed escorts in recent weeks but were intercepted and expelled shortly after they slipped into Algeria.

He said these Syrians had transited Turkey, Jordan, Egypt, Sudan and Niger or Mali using fake Sudanese passports.

Algeria has taken in around 50,000 Syrians on humanitarian grounds in recent years, Kacimi added.

Algeria went through years of devastating civil war with Islamist militant groups in the 1990s. While violence is now greatly diminished, sporadic attacks continue in isolated areas.

In Algeria’s south and southeast, largely desolate areas with few inhabitants, the government has beefed up its security presence after neighboring Libya and northern Mali and Niger descended into lawlessness with various armed groups active.