TUNIS (Reuters) - Tunisian protesters riled over economic deprivation clashed with police on Wednesday and at least 100 people were injured, medical sources said, in further unrest in the country that spawned the Arab Spring uprisings.

Now ruled by an elected Islamist-led government, Tunisia has struggled to revive its economy in the face of a decline in trade with the euro zone and disputes between secularists and Salafi Islamists over the direction of the North African state.

The street clashes began on Tuesday when thousands of people rallied in Siliana, a city in Tunisia's economically deprived interior on the edge of the Sahara desert, to demand the resignation of local officials.

"There are at least 100 wounded and some in critical condition were transferred to other hospitals," Taher Amri, an official in Siliana Hospital, said by telephone. He said police used tear gas and rubber bullets on protesters.

State television said that at least 80 people were injured and that residents blocked the entrances to the city, setting tires alight on roads.

Iyed Dahmani, a politician from the Republican Party in the town, said the national guard - an interior ministry-run security force - had deployed tanks to help restore order.

The protests were the fiercest since Salafi Islamists attacked the U.S. embassy in Tunis in September over an anti-Islam film made in California. That violence left four people dead.

Prime Minister Hamadi Jebali has accused both Salafis and liberal elites of harming Tunisia's economy and image through their conflict with each other. His Ennahda party has tried to present itself as a middle way between liberals and Salafis.

The World Bank on Tuesday approved a $500 million loan to Tunisia to help it recover from the uprising that toppled its former regime, with another $700 million loan coming from other donors.

The loan, the World Bank's second since the revolution, aims to support Tunisia's economic recovery by providing funds to improve the business and financial sectors and reform social services, which are vital for reducing inequality.

The Arab Spring democracy movement began in Tunisia almost two years ago with the fall of dictator Zain al-Abidine Ben Ali in an uprising after 23 years of rule. Subsequent uprisings toppled rulers in Egypt, Libya and Yemen, and Syria's president is battling an armed revolt that evolved from peaceful protests.

(Reporting By Tarek Amara; Writing by Tarek Amara and Andrew Hammond; Editing by Mark Heinrich)