The Under-Secretary-General for Humanitarian Affairs called for unimpeded access, and said a United Nations team should be able to get on the ground in Rakhine in the next few days.
The conflict between the country's Buddhists and Muslims, which actually originates from the 19th century, intensified on August 25, 2017, when Muslim insurgents of Rohingya origin attacked security posts in Rakhine.
Prominent human rights groups have reported documented cases of systematic attacks by the Myanmar military and Buddhist extremists against Rakhine's Muslim population, including random shootings, rape and arson attacks.
Over the past weeks, almost 510,000 Rohingya Muslim refugees have crossed Myanmar's borders into Bangladesh, where they are staying at refugee camps in the Cox's Bazar border district.
Mofazzal Hossain Chowdhury Maya, minister for disaster management and relief, said all the Rohingya would eventually be moved from 23 camps along the border and other makeshift camps around Cox's Bazar to the new zone.
The UN has "substantial capacity" in Myanmar which can be quickly deployed to northern Rakhine once clearance is granted he added.
India had also called for implementation of the Kofi Annan Commission recommendations as a solution to the crisis.More news: Microsoft Edge market share collapsed once again
"Half a million people do not pick up sticks and flee their country on a whim", Mr. Lowcock added, stressing that the scale of the exodus was evidence of a severe crisis in northern Rakhine.
The stress on Bangladesh has been increasing as the inflow of refugees continues even after nearly more than 40 days after the first instance of violence on 25 August.
Worldwide aid groups fear tens of thousands of Rohingya Muslims who remain in northern parts of Rakhine are in urgent need of food, medicine and shelter after over a month of military operations.
Myanmar has closed most access to the area, but a couple of agencies have offices open there and the International Committee of the Red Cross is helping the Myanmar Red Cross to deliver aid.
Local officials in Rakhine said Monday's tour includes meetings with relatives of victims allegedly killed by Muslim militants during the violence against Mro and Daignets minority Hindu communities in Maungdaw township.
Scores of Rohingya villages have been torched.
A previous controlled tour for diplomats scheduled for last week was abruptly canceled.