GENEVA : The World Health Organization voiced concerns Tuesday about potential disease outbreaks in Venezuela with local health services overwhelmed following deadly earthquakes.

"The health services are under extreme pressure now, with facilities operating beyond the capacity," spokesman Christian Lindmeier told a press conference in Geneva, noting the surge in trauma cases.

By the latest official count, some 1,700 are dead and 5,000 are injured, with no governmental word on the number of missing. Other estimates place these in the tens of thousands.

The WHO also said there were problems with adequately registering casualties and tracking missing persons following the 7.5- and 7.2-magnitude earthquakes on Wednesday.

"There's an increased risk now of outbreaks of vaccine-preventable diseases" such as measles and diphtheria, said Lindmeier, due to low pre-earthquake vaccination coverage, as well as yellow fever, and other vector- and water-borne diseases, including malaria, dengue, chikungunya and Zika.

He said Venezuela's interim president Delcy Rodriguez had reported that 38 hospitals had been affected by the twin earthquakes.

As of Saturday, the WHO has gathered data from 21 health facilities across Caracas La Guaira, Miranda and Falcon.

Of those, three are in critical condition; six have structural damage or are only partially functional, while the others remain operational but under "significant strain", said Lindmeier.

"Preliminary findings reveal chaotic service delivery and patient flow, marked by overcrowding; growing surgical backlogs especially under mainly trauma, orthopedics, and neurosurgery; breakdown in biosafety measures; and severely stressed staff," he said.

"Critical gaps include the collapse of forensic and morgue services, and inadequate casualty registration and tracking of missing persons."

UNHCR, the UN refugee agency, warned that community tensions were rising in quake-hit areas due to constrained aid access.

UNHCR said it needs an estimated $14.85 million to scale up protection, and provide core relief items and temporary shelter support for 30,000 earthquake-affected people over the next six months.

And Doctors Without Borders (MSF) said it was planning assistance for thousands of people left homeless.

"As the acute search-and-rescue phase comes to an end, both the number of people killed and the needs of survivors continue to rise."

It said psychological support services were being scaled up, as the needs in this field were "extremely high".