TUNIS- Tunisia and the International Monetary Fund appear to be at odds over when the next tranche of an IMF loan will be released, after a row within Tunisia's coalition government stalled the country's economic reforms.

The outcome of the talks will decide on a loan worth $250 million, part of $2.8 billion plan, and more importantly, whether Tunisia might get to sell Eurobonds worth $1 billion next month.

The IMF has been pressing Tunisia to trim its budget deficit and increase fuel and electricity bills to offset a rise in oil prices that is undercutting already-strained public finances.

The economy has been in turmoil since the toppling of autocrat Zine El Abidine Ben Ali in 2011. Inflation and unemployment are hovering near record highs.

A IMF delegation has been in Tunis for almost two weeks to discuss how to save an extra 1 billion dinars ($364.51 million) this year caused by a higher-than-expected energy bill.

The Washington-based fund has been lenient handing out loans tranches to acknowledge Tunisia's democratic transition since 2011, but patience is wearing thin. The U.S. abstained from voting at a loan review earlier this year, and the IMF is now reviewing economic progress every three months.

"The IMF has become more strict in these negotiations and has made its demands clear not to pay off the (next) instalment unless its terms are met," said Ezzidine Saidane, a local analyst.

The powerful UGTT union has stopped plans to sell state companies such as Tunisair, which has 8,000 employees but has grounded planes because it can't pay for spare parts.

POLITICAL INFIGHTING

Prime Minister Youssef Chahed has been undermined by his secular Nidaa Tounes party, which has tried to sack him. The co-ruling moderate Islamists of the Ennahda has rejected that but don't want him to run in next year's election. That has left him a lame duck who can't make tough decisions, analysts said.

The government's only option has been to raise taxes and cut fuel and other subsidies. It has raised pump prices three times this year, but a source close to the talks said the IMF wanted to increase the frequency to more or less monthly increases and to raise electricity rates.

"If the government did this it would face street protests," the source said.

The IMF team is due to leave on Friday. If no agreement is reached in the next few weeks, it might be difficult for the fund to prepare a new loan proposal until its next board meeting at the end of September, a source close to talks said.

Without an IMF report showing progress, Tunisia might find it had to sell Eurobonds worth $1 billion to help cover the deficit.

"The government appears to be in a more complex situation than ever before, especially as it has started negotiations with the UGTT in light of declining purchasing power," Saidane said. "The government may raise gasoline prices ... but it may not be enough to get the next instalment of the loan."

($1 = 2.7434 Tunisian dinars)

(Editing by) ((Ulf.Laessing@thomsonreuters.com; Reuters Messaging: follow me on twitter @ulflaessing))