United Nations officials have confirmed to VICE News that aircraft from the Saudi-led coalition struck a rehabilitation center for the blind in Yemen's capital Sanaa early on Tuesday morning.

A spokesperson for the UN High Commissioner for Human Rights said that an airstrike hit the Al Noor Center for Care and Rehabilitation of Blind, in the Alsafyeh area of Sanaa. A UNICEF official in the capital also confirmed the strike.

Though posts on social media described the center as a school for blind children, the services it offered and to whom were not immediately clear. However, Mohammed Al-Asaadi, a spokesperson for UNICEF in Sanaa, said that the facility did offer special classes for visually impaired students. As of publication, the number of casualties, if any, was also unknown. A request for comment sent to the Saudi mission to the UN had not been answered by the time of publication.

Also on Tuesday morning, the UN Office of the High Commissioner for Human Rights released updated casualty figures for the conflict, which escalated in late March when the Saudi-led coalition began targeting Houthi rebels and their allies loyal to former president Ali Abdullah Saleh.

In a statement, OHCHR spokesperson Rupert Colville said that at least 81 civilians were killed across Yemen in December, and a further 109 injured. Since late March, the UN has confirmed 2,795 civilian deaths in Yemen. As has been the case throughout the conflict, the majority of the deaths recorded by the UN in December — at least 62 — were attributed to coalition airstrikes.

Colville added that the UN had received "alarming information on the alleged use of cluster bombs by coalition forces" in Hajjah Governorate.

"During a field visit to the village of Al-Odair, in Haradh District, an OHCHR team found remnants of 29 cluster submunitions near banana plantations," said Colville. "According to witnesses, several other villages in the same area have been affected."

Watchdog groups, including Human Rights Watch, have previously documented the use of cluster munitions in Yemen. The weapons, which historically have had a high failure rate, are banned under the 2008 Convention on Cluster Munitions. Saudi Arabia is not party to the treaty, nor is the United States, which has sold cluster bombs to Riyadh as well as to the United Arab Emirates, another coalition member. Despite supplying Gulf nations with tens of billions in weapons, running a command center to offer the Saudis with "targeting assistance," and flying thousands of refueling missions for coalition aircraft, the US does not consider itself a member of the Saudi-led alliance in Yemen.

"Supporters of the Saudi-led coalition, such as the US and UK, should pay attention to ours and OHCHR's findings that these weapons are killing and wounding civilians and should demand an immediate stop to the use of these nasty weapons," said Ole Solvang, deputy emergencies director at Human Rights Watch.

Watch the VICE News documentary Inside War-Torn Yemen: Sanaa Under Attack:

Elsewhere in Yemen, OHCHR said it was particularly concerned by the ongoing humanitarian catastrophe in Taiz, where Houthi forces have prevented humanitarian aid from reaching more than 200,000 trapped residents.

"Strict control of all entry points into the city by the Popular Committees affiliated with the Houthis has resulted in limited access to essential items, including food, and made conditions extremely difficult for the civilian population," said Colville. Humanitarian officials have previously told VICE News that thousands of tons of food have been delivered to the vicinity of the city, but cannot be moved to areas in need. Colville added that at least 11 civilian deaths last month could be attributed to shelling carried out by the Houthis and their allies.

UN-brokered peace talks in Switzerland broke down last month without achieving significant results. A second round of negotiations is set for the middle of January, but may be complicated by growing tensions between Saudi Arabia and its regional foe Iran, which the Saudis accuse of backing the Houthis. On Saturday, the Saudi government announced the execution of 47 prisoners, including Nimr al-Nimr, an influential Shia cleric who had helped lead anti-government protests in 2011. That night, crowds gathered outside the Saudi embassy in Tehran and later stormed the building, lighting parts of it on fire. Saudi Arabia and several Gulf allies responded by severing diplomatic ties with Tehran.