South African police have arrested two Thai nationals in separate incidents for allegedly attempting to smuggle endangered parrot eggs out of the country as authorities try to stem the tide of wildlife trafficking.

A 50-year-old Thai national was arrested at OR Tambo international airport in Johannesburg on 20 August, carrying 50 bird eggs in a homemade incubator in a hand-luggage bag, South Africa’s environment ministry said in a statement.

The ministry said that preliminary investigations indicated that the eggs were from parrot species listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites), which regulates international trade in wild animals and plants to ensure species do not become extinct. It did not specify which species.

Another Thai national, a 23-year-old, was arrested at the same airport on 16 July, allegedly trying to smuggle 418 parrot eggs in two homemade incubator bags. Thailand’s embassy in South Africa did not immediately respond to a request for comment.

South Africa is battling wildlife smuggling on several fronts, from poached rhino horns and the bones of illegally farmed tigers to abalone shellfish and succulent plants.

The environment ministry said: “The illegal collection and trafficking of parrot eggs pose a serious threat to wild bird populations and animal welfare. Eggs are often concealed in improvised incubation devices and transported under conditions that significantly compromise their viability and endanger the welfare of developing embryos and hatchlings.”

Staff at the National Zoological Garden in Pretoria are incubating the seized eggs, the ministry said. “Several of the rescued eggs have successfully hatched and the chicks are receiving intensive veterinary and husbandry care to maximise their chances of survival,” the statement added.

The ministry said the arrests were carried out after a “joint intelligence-driven operation” led by its Environmental Management Inspectorate, known as the “Green Scorpions”, and police intelligence, border and endangered species units.

South Africa punishes the illegal export of Cites-listed species with a fine of 10m rand (£460,000), up to 10 years in prison or both.