The UN also slammed the level of access granted by Myanmar to the heart of the refugee crisis as "unacceptable".
The UN has described the government-sanctioned crackdown on Rohingya as "a textbook example of ethnic cleansing".
Refugees are living in camps near the border amid claims that hundreds of villages were torched in an apparent attempt to force Muslims out of the Buddhist-majority country.
Aid agencies have warned of a malnutrition crisis with about 281,000 people in Bangladesh in urgent need of food, including 145,000 children under five and more than 50,000 pregnant and breastfeeding women.More news: United Kingdom scientist among Nobel Prize winners for 3D molecule imaging
There may be up to 100,000 more people in northern Rakhine waiting to cross into Bangladesh, according to the International Organization for Migration.
Cholera is a risk, amid fears of disease spreading in the rain-drenched camps where aid workers are trying to install sanitation systems, a spokesman for the World Health Organisation said.
The exodus from Myanmar to Bangladesh started in late August, when Rohingya militants attacked police posts in Rakhine, triggering a major security operation by the government of the Buddhist-majority country.
Former Labour MP Chris Carter is the United Nations official in charge of Rakhine State.
Addressing a joint press event, Tusk said the two sides wanted de-escalation of tensions and full adherence to global obligations in Myanmar and access of people to humanitarian aid.More news: Greek Court Approves US Extradition Of Suspected BTC-e Operator Alexander Vinnik
Lowcock said he believed "a high level" United Nations team would be able to visit the area "in the next few days".
The OIC had made a stand that the refugees should be allowed to return safely to Myanmar and that Naypyidaw should take concrete measures to handle the deadly conflict which had occurred mainly in the Rakhine province which borders Bangladesh.
Myanmar leader Aung San Suu Kyi has faced criticism for not doing more to stop the violence, although a military-drafted constitution gives her no power over the security forces.
STRESSING THAT he has not seen any sign of radicalisation among Rohingya refugees, Bangladesh Foreign Secretary Shahidul Haque Friday said that he would not comment on India's move to deport them but hoped that "in the end... humanitarian issues will get due consideration".More news: Tesla Misses Model 3 Production Prediction By Miles