Immigration authorities in Botswana said on Friday that the repatriation of almost 2,500 illegal Zimbabweans each month was a drain on resources.
Chief immigration officer Roy Sekgororoane told IRIN that about 150,000 pula (US $32,000) was being spent every month on food for the illegal immigrants and transporting them across the border.
Since 2002 Zimbabweans have flocked to neighbouring Botswana in search of economic opportunities. The influx has sparked reports accusing Botswana officials of ill-treating Zimbabweans in the country, but Sekgororoane denied the allegations, saying, "if there are incidents of ill-treatment", these were "isolated".
"There is no systematic attempt to mistreat the Zimbabweans. If this is occurring, we have called for the incident to be reported immediately, and action will be taken against the perpetrators," he said.
He also denied that an electric fence Botswana has been constructing on its frontier with Zimbabwe was to control the movement of illegal immigrants from Zimbabwe.
"The fence has nothing to do with keeping people out of the country. Neither the immigration department nor the home affairs ministry has anything to do with its construction - this is an initiative of the ministry of agriculture and is aimed at controlling the movement of livestock," Sekgororoane said.