TUNIS - Tunisia's ruling party has suspended Prime Minister Youssef Chahed in the latest escalation of a row with the president's son that has paralysed key decisions on the troubled economy.

The North African country is often portrayed as the lone success story of the Arab Spring of 2011 but more than seven years after the ouster of longtime strongman Zine El Abidine Ben Ali it is still battling high inflation and unemployment and sometimes violent social unrest.

Nidaa Tounes announced Chahed's referral to its disciplinary committee late on Friday after he delivered a stinging attack on infighting within the party that he said was restricting his government's ability to revive the economy.

"Secondary political conflicts.. have disrupted the work of the government, holding it back and blocking the reform process and the decisions necessary to achieve economic growth," he said in a televised address to a policy conference.

The ruling party is led by President Beji Caid Essebsi's son Hafedh, who has been battling to oust the premier for months.

The power struggle previously came to a head in July, when the president himself called on Chahed to resign.

The move received the backing of the powerful UGTT trade union confederation, which opposes the programme of austerity budgets and privatisations of state enterprises championed by the prime minister.

But Chahed was saved by the Islamist Ennahdha party, the second largest in parliament, which said it was important for Tunisia's stability that the prime minister remain in post.

Chahed, who took office in August 2016, is the seventh prime minister since the revolution and already the longest serving. He also has the ear of Western donors.

The premier has since been preparing for any new moves against him, by forming his own separate grouping within Nida Tounes.

He can count on the backing of around 40 lawmakers - nearly half of the party's parliamentary bloc.

The deepening rift within the ruling party comes as the government faces a mid-October deadline to unveil a 2019 budget.

Inflation, which is projected to average 7.8 percent this year, and unemployment, which has remained stubbornly over 15 percent, helped stoke an outbreak of violent unrest in January.

But analysts expressed concern that political considerations might prompt the abandonment of any tough or potentially unpopular new policy initiatives to tackle them.

"The country is completely absorbed by short-term political manoeuvring by the personal ambitions of one person or another, to the detriment of pressing economic decisions, social priorities and structural reform," said political scientist Hamza Meddeb.

Analyst Selim Kharrat warned that the infighting could result in a "budget stripped of any initiative to tackle inflation or youth unemployment".