United Nations: The UN has described the decision by Crimean authorities in Ukraine to hold a referendum as a "worrying and serious development" saying that the concerned parties should consider the implications before taking any hasty actions "in the heat of the moment". "The recent announcement by the authorities in Crimea that they intend to hold a referendum is a worrying and serious development," UN spokesperson Martin Nesirky said yesterday. "In this regard, the Secretary-General urges the authorities in Ukraine, including in Crimea, to treat this matter with calm." Nesirky said it should be noted that referendums usually have clear rules on national constitutional law that should be looked into "carefully and?dispassionately". "All concerned should think about the implications of any hasty actions or decisions taken in the heat of the moment. The Secretary-General cannot emphasise enough the need for peace and stability in the region," he said referring to UN Secretary-General Ban Ki-moon emphasising the need for peace and stability in Ukraine`s Crimea region. Lawmakers in Crimea voted to join Russia and to hold a referendum on March 16 to validate the decision. The move comes amid rising tensions in the region, where additional Russian troops and armoured vehicles have recently been deployed, and against the backdrop of the protests and violence that have plagued Ukraine since last November. Nesirky said that the Secretary-General`s Senior Advisor, Robert Serry, is continuing his consultations with Ukrainian and diplomatic interlocutors in Kiev?before leaving the country today. Serry would return to Jerusalem next week, where he is based as the UN Special Coordinator for the Middle East Peace Process. "At this stage, it is not yet known when he will return to Ukraine," Nesirky said. "But he will continue to assist the Secretary-General, as required, in his good offices to promote urgently needed de-escalation and a peaceful political resolution of the country`s current crisis," he said. Meanwhile, Assistant Secretary-General for Human Rights Ivan Simonovic arrived in Ukraine to conduct a preliminary assessment of the rights situation after recent developments. He will "seek to identify existing and potential human rights challenges and to advocate for the protection of human rights, including those of minorities, as well as for accountability for recent human rights violations," Rupert Colville, spokesperson for the Office of the UN High Commissioner for Human Rights (OHCHR), said in Geneva. During his eight-day visit, Simonovic plans to meet authorities in the capital, Kiev, as well as in Lviv, Kharkiv and Simferopol, as well as the Ombudsman, and civil society organisations at central and regional levels. He will also liaise with regional organisations active in Ukraine, especially the Organisation for Security and Cooperation in Europe (OSCE) , its Office for Democratic Institutions and Human Rights, and the Council of Europe.