Gambia's top judge has been sacked by President Yahya Jammeh after just six months on the job, a judicial official said on Wednesday.

Ghanaian-born chief justice Mabel Yamoa Agyemang "has been relieved of her appointment effective Monday [3 February ]", the senior judicial officer told AFP, without giving a reason.

Agyemang replaced Nigerian-born Joseph Wowo, who became mired in a bribery scandal in July last year and was jailed on a string of corruption charges in January.

She had been practising law in The Gambia since 2004, when she was appointed as an expert appeal court judge after working in her native Ghana.

The president regularly reshuffles his cabinet in what many observers say is a sign of insecurity, and runs several key ministries himself, including defence and religious affairs.

Jammeh sacked five cabinet ministers in August as part of a ruthless shake-up of the government and judiciary which saw his justice minister lose her job.

Jammeh, who has ruled mainland Africa's smallest country with an aura of mysticism and an iron fist since seizing power in 1994, vowed ahead of his swearing-in for a fourth term in 2012 to eradicate corruption.

In the same year, former information minister Amadou Scattred Janneh was sentenced to life in prison for treason for distributing T-shirts which featured the slogan "End to Dictatorship Now".

A sliver of land nestled within Senegal, The Gambia has over the years also seen the arrest and jailing of a number of senior military and police officers for crimes relating to treason, drug trafficking and corruption.