TEGUCIGALPA - Ousted Honduran President Manuel Zelaya departed on a flight for his country on Sunday, but the interim government that has defied international pressure over last week's coup said it would not let his plane land.

The aviation authority in Honduras, which has been slapped with suspension from the Organization of American States over its refusal to reinstate Zelaya, said Zelaya's plane had been directed to go to El Salvador.

Zelaya had left Washington shortly before on a chartered plane, accompanied by U.N. General Assembly President Miguel D'Escoto, according to Venezuela's foreign minister and Caracas-based Telesur regional television, which showed images of the ousted president boarding an aircraft.

I am sure that in the next few hours we will be telling you about our arrival in this plane in the capital of Honduras, Tegucigalpa, Zelaya said.

Zelaya, a leftist who had been due to leave power in 2010, was bundled out of office at gunpoint by troops and flown into exile in Costa Rica a week ago in a coup that has been widely condemned abroad.

In Honduras, Enrique Ortez, foreign minister of the caretaker government installed hours after the coup, said before Zelaya left Washington that any aircraft carrying him would not be allowed to land. The interim government has already said Zelaya will be arrested if he enters Honduras.

I have given orders that he not be allowed back. We cannot allow recklessness, Ortez told local radio.

In Tegucigalpa, thousands of Zelaya supporters, some carrying sticks, rallied to back his return. Troops and police tightened security and around the main airport.

OAS SLAP

Zelaya's plan to return followed the strongest move yet by foreign governments to isolate the caretaker government since the coup -- which was the first in Central America since the Cold War era and was triggered by a dispute over presidential term limits.

The OAS met into the early hours of Sunday in Washington and took the rare step to suspend Honduras after the interim authorities ignored an ultimatum by the 34-member body to reinstate Zelaya.

OAS Secretary-General Jose Miguel Insulza, Argentine President Cristina Fernandez and Paraguayan President Fernando Lugo planned to travel to El Salvador to monitor Zelaya's return, said Ecuadorean President Rafael Correa, who also planned to be in that group.

Honduras, a coffee and textile exporter with a population of around 7 million, is the third poorest country in the hemisphere after Haiti and Nicaragua.

The OAS suspension could complicate access to credits from regional lender Inter-American Development Bank for Honduras. The IADB said last week it was suspending loans over the coup.

Zelaya, a businessman who edged to the left after he came to power in 2006, upset traditional elites, including members of his own Liberal Party, with what critics say was an illegal attempt to lift presidential term limits and by establishing closer ties with Venezuelan President Hugo Chavez, a U.S. foe.

Several countries at the OAS meeting had advised against the ousted president's plan to return, and a local church leader warned of possible violence if he tried to go home.
The Obama administration, European governments and Zelaya's left-wing allies have condemned his ouster. The caretaker government, installed hours after the coup, has said it legally removed a president who violated the constitution.

The coup has thrown up a test for regional diplomacy and for President Barack Obama's ability to mend the battered U.S. image in Latin America, where Chavez has used his oil wealth to spread a message of socialist revolution to counter U.S. influence.

The Obama administration has so far given the OAS the lead role in seeking a solution. It has also held off on issuing a legal determination of the ouster as a coup -- a definition that would force a cutoff of aid to the country.

(Additional reporting by Alonso Soto in Washington, and Gustavo Palencia and Mica Rosenberg in Tegucigalpa, Editing by Frances Kerry)