MOGADISHU, May 21 (Xinhua) -- At least 16 people were killed after Tropical Cyclone Sagar caused heavy rainfall in Somaliland in northern Somalia over the weekend, the UN humanitarian agency said on Monday.

In its Flash Update on the Tropical Cyclone Sagar, the UN office for Coordination of Humanitarian Affairs (OCHA) said the deadly storm which had formed in the Gulf of Aden between Yemen and northern Somalia destroyed the homes of some 80 families and left at least 1,780 others displaced.

"Tens of thousands of people have been affected by flooding, displacement and the destruction of infrastructure in Sagar's wake," said the UN humanitarian agency.

"Due to the dispute over the regions of Sool and Sanaag and lack of access to some affected areas after the destruction of roads, the situation of affected populations and impediments caused by blocked roads and failed communications, the extent of the damage is yet to be fully confirmed," OCHA said.

Heavy rainfall, strong winds and dangerous flash floods that hit coastal areas of Puntland and Somaliland on Saturday resulted in the loss of lives, crops and livestock as well as the destruction of property and infrastructure.

In Somaliland, the UN said the largest concentration of fatalities was reported in coastal Galbeed and Awdal, where the cyclone made landfall. Houses were destroyed, and livestock washed away.

"The heavy rains and subsequent flooding are hindering humanitarians' ability to access some of the areas affected by the cyclone to assess the extent of the damage and provide assistance," said OCHA.

Sagar was observed in the northern region of Bari, with Bareeda, Caluula, Murcanyo, Gumbax, and some parts of Xaabo being amongst the worst affected areas

It said the cyclone has worsened the humanitarian situation in Somaliland and Puntland states and disputed regions, which have experienced protracted drought dating back to 2015, leaving them particularly prone to flash flooding in the direct aftermath of massive downpours.

According to local Somaliland authorities, scores of fishing boats went missing in the region. Reports also suggest that about 40 fishermen were at sea before the cyclone alert was announced and their fate is unknown.

Meanwhile, OCHA said forces from Puntland and Somaliland have been engaged in an armed standoff in Sool that had displaced almost 10,000 people prior to the cyclone's arrival, further complicating an already complex humanitarian picture.

"By the morning of May 20, meteorological authorities were reporting that Sagar was beginning to weaken into a tropical depression. The tropical depression itself has remained over parts of Ethiopia, Djibouti and north-west Somaliland, about 140 km from Hargeisa," it said.

Sagar was named by UK Meteorological Office on May 16 after beginning life as a tropical depression (1A) in the Gulf of Aden.

The UK office adds the forecast appears to be a severe as the 2013 Somali Cyclone, but slightly below the severity of the 2008 Yemen Cyclone. However, much will depend upon the track of the cyclone over the coming days.