The death toll from last week's twin earthquakes in Venezuela has climbed to more than 3,500, while nearly 18,000 people remain homeless, raising fears of a worsening public health crisis.

Lawmaker Jorge Rodriguez said on Monday that the official death toll had reached 3,535. The earthquakes also injured 16,740 people and left 17,854 without homes.

At least 12,800 displaced people are now staying in 80 temporary shelters across Caracas and the coastal state of La Guaira, the areas worst affected by the disaster.

The powerful earthquakes, measuring 7.2 and 7.5 in magnitude, struck within seconds of each other on June 24, causing widespread destruction in and around Caracas and La Guaira. Around 60,000 buildings were damaged or destroyed.

In La Guaira, Reuters witnesses saw trucks carrying coffins and forensic teams working as heavy machinery dug burial trenches in an area marked with white crosses.

Health experts have warned that the disaster could trigger a major public health emergency as thousands of survivors continue to live in overcrowded shelters or outdoors without clean water or proper sanitation.

Many people are still suffering from untreated injuries, while infectious diseases are becoming an increasing concern as Venezuela's already strained healthcare system struggles to cope.

"The next major challenge will be infections among people who have been exposed to the disaster for a long time," said Eugenio Cova, head of the trauma unit at Hospital Jose Gregorio Hernandez in Caracas.

He said hospitals were continuing to treat patients with serious injuries, but infections were making the situation more difficult.

Reports of illness are already increasing. Residents in temporary shelters have complained of diarrhoea and other diseases, while calling for portable toilets, better sanitation and government support to reduce overcrowding and prevent the spread of infections.

Meanwhile, frustration is growing over the government's rescue and relief efforts. In many affected communities, local residents, volunteers and humanitarian workers have taken the lead in searching for survivors and distributing aid.

Carolina Jimenez, president of the Washington Office on Latin America (WOLA), said the government's response had been inadequate.

"In most countries, the state is the first responder after a disaster. In Venezuela, the state has been the last responder," she said.

In areas such as Catia la Mar, north of Caracas, residents said government assistance had either not arrived or remained insufficient, forcing volunteers and civil society groups to fill the gap.