LONDON/PARIS (Reuters) - International banks and insurers will meet today to thrash out a plan for the private sector to contribute to Greece’s bailout effort as fears grow that the proposal will be derailed.The Institute of International Finance (IIF) lobby group said it will chair the meeting of private-sector creditors.It needs to resolve how a deal can get past credit rating agencies without it being termed a default, and how accountants will deal with it.A lot of work remains to be done and today’s meeting will not be decisive, several sources said.“It’s a process. The new French finance minister said today it will take weeks, over the summer. It’s complex. It can’t be settled overnight,” a French private sector source involved in the talks said.He said there was unlikely to be a single “one-size-fits-all solution” but rather several options, given the number of different bondholders and stakeholders involved.“The issue is so complex that we need more time,” a German banking industry source added.French banks, major holders of Greek sovereign debt, have proposed voluntarily renewing Greek bonds when they fall due. Bondholders would reinvest at least 70 percent of the proceeds from bonds maturing between now and the end of 2014 in new 30-year Greek debt.The Financial Times said a new proposal, sweetened to be more attractive to Greece, would be presented at today’s meeting, lowering the interest rate and raising the proportion of debt targeted for rollover in the French plan.