Marketing director Vernon Wait said a 28-year-old cow, an eight-year-old pregnant bull, another eight-year-old bull and a three-year-old male were killed and had their horns removed.

Wait said the rhinos were probably poisoned before their horns were removed.

He said the method used by the poachers was "very professional".

"Unlike usual incidents of poaching where the horns are hacked off with pangas or axes, in this case, the horns were "clinically" cut off... very professional."

The game reserve's Facebook page reported that there were no visible bullet wounds on any of the rhinos and it was likely that they were poisoned.

The Democratic Alliance in the province condemned the killings.

"The DA condemns the massacre of four rhinos at the Lalibela Game Reserve and insists that MEC Mcebisi Jonas takes it as a warning of things to come," said DA spokesman John Cupido.

He said only rhinos from privately owned game reserves had been poached this year in the province.

"So far none of the rhinos lost to poaching in the Eastern Cape this year have been on state reserves, but this lucky streak will not last," he said.

Cupido said if the Green Scorpions were not improved, there would be astronomical losses in game reserves, as poachers would start targeting state owned reserves too.

"The Green Scorpions are staffed with dedicated rangers, but is severely under-equipped... an immediate concern is the unit's lack of vehicles," said Cupido.

He said the DA would submit parliamentary questions to the MEC to find out how under-equipped the Green Scorpions were and how the MEC planned to increase security on game reserves.

The office of the MEC was not immediately available for comment.

Two weeks ago, the department of environmental affairs said 381 rhinos had been killed in 2012 alone.

It said the provinces which were hardest hit by rhino poaching included Limpopo, KwaZulu-Natal and the North West.

Police were investigating the poaching incident at the Lalibela game reserve.