A mother has taken the government to court to force it to get her son back home from a Mauritian prison where he is serving a long jail term for possession of drugs.

Patricia Gerber approached the Pretoria High Court in an attempt to compel the government to have her 24-year-old son, Johann Gerber, transferred to a South African jail to serve the remaining years of his sentence.

Johann was arrested when he was 20 in Mauritius in August 2005 and convicted for importing heroin.

He is serving an 11-year sentence in the Beau-Bassin Prison and is due for release in 2016.

His mother says his incarceration in far away Mauritius has caused her tremendous suffering and has become a heavy financial burden.

She is pushing for her youngest son to be transferred to a South African prison so that he will be closer for family and friends to visit him.

In court papers, Gerber says the government has the power to enter into prisoner transfer agreements with Mauritius and the authority to consider her request rationally, in good faith and in accordance with the principle of legality.

She has been negotiating with the Department of Foreign affairs since November 2007 in an effort to get her son back to South Africa.

But in a letter to her in November 2007, the department said her son was not the only prisoner held in Mauritius, and that South Africa had committed to supporting international efforts aimed at combating serious crimes.

Gerber says the government acted irrationally.

"The state is dependent for its very existence and derives all its powers and functions from the Constitution," she says in court papers. The government had told her the relief she sought would amount to a dictation of the conduct of foreign policy relations to the executive authority, and that the government should not be compelled to conclude international agreements.

The government said citizens who left the country would have to endure the consequences of their unlawful or illegal conduct.

"They should not be tempted to engage in such conduct on the assumption that the government will intervene on their behalf by concluding prisoner transfer agreements," it said.