Jordan's health minister made an "urgent appeal" on Tuesday for around $355 million to provide medical care for hundreds of thousands of Syrian refugees who have sought safety in the kingdom.

Mjalli Mheilan told state-run Petra news agency that the total number of Syrians in Jordan had now reached one million, a sharp rise on the previous figure of more than 475,000 given by Jordanian authorities.

It compares with a UN figure given last Friday of some 385,500 UN-registered Syrian refugees in Jordan, a number the UN refugee agency warned it expects to rise to 1.2 million by the end of the year.

"The health situation in Jordan is still under control, but negative indications have started to appear," the Jordanian minister said.

"The health ministry needs an urgent assistance of 250 million dinars ($355 million) to address the health situation of the Syrian refugees."

In all, 1.3 million refugees have fled Syria to neighbouring countries since the conflict erupted in March 2011, the regional aid coordinator for the UN High Commissioner for Refugees, Panos Moumtzis, said on Tuesday.

An additional 200,000 refugees are fleeing each month, Moumtzis added, warning that aid operations were at "breaking point."