At least 120,000 people have been displaced by fighting in the Syrian provinces of Aleppo, Hama and Idlib since the beginning of October, the United Nations said on Monday.
"This is up from 50,000 we reported last week," Vanessa Huguenin, spokeswoman for the UN's Office for the Coordination of Humanitarian Affairs (OCHA), told journalists in Geneva.
She added that most of those displaced by the latest violence have stayed in their provinces, but others have also fled to camps in the Qah area near the Turkish border.
The conflict has killed more than 250,000 people dead since it broke out in March 2011, sparked by a bloody crackdown on protests against the rule of President Bashar al-Assad.
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The conflict has since morphed into a multi-sided civil war with various different actors, with Russia the latest to enter the fray by launching air strikes against forces hostile to its ally Assad.
Moscow announced Monday that it had hit a record 94 Syrian targets over the last 24 hours -- including in the Aleppo, Hama and Idlib provinces.
Moscow says it is targeting the Islamic State group and other "terrorists," but Syrian rebels and their backers say Russian strikes have focused on moderate and Islamist fighters, not jihadists.
"People need tents, basic household items, food and water and sanitation services," Huguenin said, adding that aid workers were continuing to mobilise and that six mobile health clinics had been set up in Aleppo to help the wounded.
"Negotiations continue regarding the provision of additional humanitarian supplies to areas covered by the ceasefire agreement," she added.
A six-month ceasefire deal, brokered by the UN, came into force in several areas last month in a bid to halt fighting between regime forces and rebel groups.