The two-day visit here by Sandinista leader Daniel Ortega Saavedra has rewarmed French ties with the Nicaraguan regime - to the evident consternation of the Reagan administration.
After meeting with Mr. Ortega Tuesday, President Francois Mitterrand announced that France would provide Nicaragua with about $10.5 million in economic aid.
Later in the day, Foreign Minister Claude Cheysson confirmed that France had begun deliveries to Nicaragua of two Alouette III helicopters, potent anti-personnel gunships that were the most controversial part of the $17 million arms contract signed last December.
Though the French officially deny it, United States diplomats here said Mr. Mitterrand delayed delivery of these helicopters until after he met met with President Reagan in March at the White House.
The US said Mitterrand, in his meeting with Reagan, agreed to cool his support of the Sandinistas as well as his support for diplomatic recognition of the El Salvador guerrillas so as not to poison relations between Paris and Washington before the Versailles summit last month.
But now Mitterrand blames Reagan for torpedoing the positive results of the Versailles gathering by imposing stiff import duties on European steel and extending the embargo on US technology for the Soviet-European gas pipeline. As a result, US diplomats here believe the French President decided there was no reason not to invite Ortega and to announce imminent delivery of the arms.
''We're not happy about it at all,'' one US diplomat said, commenting on the arms deliveries.
Foreign Minister Cheysson denied that the French have rekindled their ties with the Sandinistas out of anger with the US. ''Deliveries of arms are following a normal rhythm,'' he said.
Still, both French and US diplomats agree that Nicaragua remains a major - until the steel and pipeline disputes, perhaps the major - cause of friction between the two countries.
The French believe US refusal to deal with the Sandinistas is driving Managua into the Soviet Union's orbit, and that French aid is the best way to assure that the Sandinistas remain truly nonaligned. In addition, France's governing Socialists do not hide their sympathy with the Sandinista's overthrow of Anastasio Somoza three years ago.
It is necessary ''to safeguard the originality of the Sandinista path,'' said Mitterrand after meeting with the Sandinista leader. It is also necessary, he stressed, ''to assure the authentic nonalignment of Nicaragua.''
The US believes this thinking is naive dreaming. Ambassador Evan Galbraith has said that the French don't understand how vulnerable the Sandinistas are to Soviet and Cuban influence.
Nicaragua, he has said, ''has become a major base for revolutionary activities throughout the region.'' He argues that French arms will not moderate the Sandinistas, insisting that Nicaragua is ''a totalitarian country'' that abuses human rights.
For his part in this dispute, Ortega firmly sided with the French.
Interviewed by the prestegious daily Le Monde before arriving in Paris, the Sandinista leader thanked France for its support of the Nicaraguan revolution and said he hoped France ''would maintain its active policy in Central America.''
And at a press conference here, Ortega said France and Nicaragua shared ''a total convergence of views'' on Central America. He called for a ''new impulse'' to the Franco-Mexican declaration of last August which, to US displeasure, urged El Salvador's government to negotiate with the guerrillas.