Thousands of Syrian refugees poured into northern Iraq, taking advantage of a new bridge along the largely closed border, with most being women, children and elderly people from areas of heavy fighting, including Aleppo and Hassakeh.
Some Syrian refugees had been allowed in since mid-July for reasons of family reunification or dire humanitarian need, the UN added.
More top news
The foreign secretary's suggestion last week's bombing of an aid convoy might constitute a war crime prompted an angry response from Moscow.
Goals from Charlie Austin, Dusan Tadic and James Ward-Prowse consigned Slaven Bilic's men to their fourth straight Premier League loss.
Showers will continue in the north and west, heavy in places.