Zine El Abidine Ben Ali is facing a total of 18 charges [EPA]

Former Tunisian president Zine El Abidine Ben Ali and his wife Leila Trabelsi have been charged with "plotting against the "internal security of the state", the justice ministry has announced.

Charges also include the "instigation of disorder, murders and looting", state media quoted ministry as saying on Wednesday.

A court in the central city of Sousse is also looking into whether the death of four youths who were shot dead in the town of Ouardanine during the unrest that led to Ben Ali's ouster, can be linked to the former presidential couple and a nephew.

Families of the four accuse security forces of having ordered to shoot demonstrators opposing the flight of the nephew, Kais Ben Ali, the TAP news agency reported.

In all, the former leader faces 18 lawsuits including homicide, drug use and drug trafficking, said justice minister Lazhar Karoui Chebbi.

He said in mid-April that the government was trying to have Ben Ali extradited from Saudi Arabia where he fled in mid-January. Tunisian authorities also asked the Saudis for details on the ousted president's health after rumors surfaced he'd been ill or possibly died.

A United Nations mission has said at least 219 people were killed in the unrest that occurred in the North African country for weeks.

A women's rights group has also alleged that security forces raped, tortured and robbed people during
the upheaval.

The Ben Ali and Trabelsi extended families were notoriously corrupt - with business interests in nearly every sector of the Tunisian economy - and the target of much public outrage after the regime fell.

'Urgent budgetary aid'

The country's tourism-dependent economy has struggled in the wake of the upheaval.

The revolution in Egypt and continued fighting in neighbouring Libya - which has recently spilled over onto Tunisian soil - have only made matters worse.

Robert Zoellick, the World Bank president, announced that the bank had granted Tunisia $500 million in "urgent budgetary aid".

Speaking at a news conference on Wednesday during a visit to the capital Tunis, he said the African Development Bank has agreed to provide the funds.

He added that the money is aimed at supporting "reforms to improve governance, transparency, laws on freedom of association, and on efforts to create jobs and promote poor regions".

Tunisia's revolution - the first of many revolts that have spread throughout the Arab world this year - began in late December in one of the country's poorest areas.