The fight to wipe out HIV, tuberculosis (TB) and malaria is losing steam and the diseases are gaining ground, according to organizations leading the international effort.

They are sounding the alarm as government officials, NGO's and others involved in the effort gather in the French city of Lyon, to announce pledges and hear the case for more funding.

The forum is the Sixth Replenishment Conference of the Global Fund, the partnership that heads up the international effort to eradicate the diseases.

These meetings mark the start of its next three-year funding cycle, during which the fund aims to raise at least $14 billion, which the organization concedes is an "ambitious" target.

The stated goal is to save 16 million lives worldwide over the next three years, in addition to the 32 million it claims to have saved since its creation.

Speaking to journalists attending the conference, the fund's head of external relations, Francoise Vanni, said the diseases were "fighting back." She warned that any complacency about the struggle would put current targets out of reach.

Hanging over the triennial meetings is a concern about declining international financial support for the mission. The Global Fund says that after years of "remarkable progress" the world is now on a path to missing the stated goal of ending the epidemics of HIV, TB and malaria by 2030.

It blames "wavering political commitment, shortfalls in funding and increasing insecticide and drug resistance." As a result, the Global Fund says the mission is at a "crucial stage" and needs to be put "back on track."

The aid group Médecins Sans Frontières/Doctors Without Borders (MSF) is throwing its weight behind the effort, with a warning that the response to HIV and TB is being "derailed." In a report published just before the conference, the organization put much of the blame on a decline in donor nation funding, driven by "international political fatigue."

"AIDS is back," said Mit Philips, a doctor with MSF, in an interview with CGTN Europe. "We see patients again in very severe stages of the disease," she said.

The MSF report, titled Burden Sharing Or Burden Shifting? notes that countries on the front line of the epidemics – many of them already facing serious economic challenges – are now under pressure to make up the shortfalls.

"The rich countries are very pessimistic about what they can contribute, while they are very optimistic about what the affected counties can contribute, but of course we need everybody to chip in," said Philips.

French President Emmanuel Macron will address the conference on Thursday.