Progress toward wiping out measles worldwide has stalled, with deaths from the highly contagious disease rising last year and poor vaccine coverage leading to large outbreaks, the World Health Organization (WHO) said on Thursday.

More than 145,000 people died of measles in 2013, up from 122,000 in 2012, the WHO said. Epidemics in China, Congo and Nigeria contributed to this, but there were also outbreaks in the WHO's European region, including in Georgia, Turkey and Ukraine.

"Failure to reverse this alarming trend could jeopardize the momentum generated by a decade of achievements in reducing measles mortality," said Peter Strebel of the WHO's immunization department. "Countries urgently need to prioritize maintaining and improving immunization coverage."

The 2013 death toll represents a 75 percent drop since 2000, significantly below the internationally agreed target of 95 percent reduction in measles deaths between 2000 and 2015.

Measles is a contagious and sometimes deadly viral disease which can spread very swiftly among unvaccinated children.

There is no specific treatment and most people recover within a few weeks, but, particularly in poor and malnourished children and people with reduced immunity, measles can cause serious complications including blindness, encephalitis, severe diarrhea, ear infection and pneumonia.

The vast majority of measles deaths are in poor countries. In 2013, more than 70 percent of global measles deaths were in six countries -- India, Nigeria, Pakistan, Ethiopia, Indonesia and the Democratic Republic of Congo.

Steve Cochi of the U.S. Centers for Disease Control and Prevention's global immunization department said the recent resurgence of measles, especially in Africa, was largely due to a drop in financial support during the global recession.

"This funding gap is only recently being closed and the world's children cannot afford yet another setback in progress," he said in a statement as the WHO published its measles report.

In developing countries, it costs around $1 to vaccinate a child against measles.

Experts note impressive gains toward wiping out measles in recent years, with an estimated 15.6 million deaths prevented by vaccination between 2000 and 2013.

But this large reduction in deaths is now tapering off, said Robert Kezaala, a health advisor at the United Nations children's fund UNICEF.

He said the funding cuts had postponed or reduced some vaccination programs and led to large measles outbreaks "that threaten our hard earned gains".

Estimated coverage with the first dose of measles vaccine rose globally to 83 percent by 2009, but it has remained static since -- standing at 83 to 84 percent through 2013.