Economists said the move, whose mechanism Khalil did not explain in detail, aimed to ease the burden of managing state debt estimated in 2017 at over 150 percent of GDP, one of the highest such ratios in the world.
"The fact they have to go down this route goes to show that policymakers are really struggling ... to deal with the dire public finances," said Jason Tuvey, Middle East Economist at Capital Economics.
Lebanon is due to hold a parliamentary election on May 6.
Khalil said that while the planned operation was not ideal and might affect markets, the state needed to secure $7.3 billion to cover maturing foreign currency payments due in 2018.
Part of this would come from revenues or through swapping bonds that had matured in recent years or were due to this year.
"There remains about $5 billion that the state still needs to issue as treasury bonds. We took the initiative to look for a framework to benefit from this in a way that strengthens the central bank assets," he told a session to discuss the draft 2018 budget.
"...We issue treasury bonds in foreign currency from which the central bank benefits, in exchange for treasury bonds for the needs of (the) Lebanese state."
Capital Economics' Tuvey questioned the sustainability of the type of operation detailed by Khalil, over which "concerns may also build about the Lebanese pound, and whether that would need to be devalued".
"I don't think devaluation is an immediate concern, but clearly there are significant risks, particularly if we saw a re-escalation of the geopolitical tensions that we saw late last year, and saw another sustained withdrawal of non-resident deposits from the banking system," he said.
Central bank governor Riad Salameh was not considering a devaluation, English-language newspaper Daily Star quoted him as saying in an interview published on Thursday.
The Lebanese pound has been pegged against the dollar at the same level for 20 years.
Salameh said this month dollar reserves at the central bank had climbed in early 2018, recovering from the decline during the Hariri resignation crisis.
Nassib Ghobril, chief economist at Byblos Bank said that, should the swap go ahead, the issuance would be for special, non-market Eurobonds. "The primary objective is to reduce debt servicing costs," he said.
The International Monetary Fund, in the concluding statement of a staff visit in February, called on Lebanon to immediately anchor its fiscal policy in a consolidation plan to stabilise debt and put it on a downward path.
Fiscal reform is a key demand of international donors due to convene an April 6 Paris conference where Lebanon hopes to secure billions of dollars of soft loans for a capital investment plan.
(Writing by Tom Perry Editing by Gareth Jones and John Stonestreet) ((email@example.com; Reuters Messaging: firstname.lastname@example.org))