An ash cloud spewed by Chile's Puyehue volcano forced the cancellation of at least two dozen flights Saturday in Uruguay, where tourists lengthened their hotel stays.

Uruguay's National Weather Service issued a yellow alert over the presence of volcanic ash in the South American country between Brazil and Argentina.

The cloud of ash "is affecting the capital of Argentina, but the bulk of the clouds will begin to enter Uruguay late afternoon Sunday and arrive late in the evening," meteorologist Nubel Cisnero told Channel 4.

He predicted a thin layer of volcanic ash would cover cars and windows and further complicate air travel from Carrasco International Airport, which serves the capital Montevideo.

At least 12 departure flights were canceled that had been due to leave for Argentina, Sao Paulo, Lima and Miami, along with another 12 arrival flights from Aerolineas Argentinas, American Airlines, GOL, Pluna, TACA and TAM, according to airport figures.

It marked the third time flights were affected by the Chilean volcano, which erupted on June 4.

The decision to suspend flights falls to airlines, concerned about how the ash will affect their aircraft's engines, as the main airport remained open.

Despite the cancellations, Tourism and Sports Undersecretary Liliam Kechichian noted that Uruguay was seeing a raft of tourists who had planned to travel to Argentina and Chile remain in the country instead.

Saturday marked the start of winter school holidays in Uruguay, which extended by two weeks the vacation that usually sees high school students travel by land to southern Argentina, where winter tourist resorts were hit hard by the ash from the Andean mountains.

Several trips from Uruguay were thus canceled or destinations were changed, according to local tour operators.

Meanwhile flights to and from the Argentine capital resumed normal schedule after being grounded by the volcanic ash on Friday.

At Buenos Aires' Ezeiza international airport, LAN Argentina airline said services were resuming "gradually," and officials with carrier Aerolineas said their flights began departing at 1400 GMT.

Services from the Argentine capital's Jorge Newbery airport, which serves domestic and neighboring South American destinations, also resumed.

The airport in the Argentine resort town of Bariloche -- some 100 kilometers (62 miles) from the volcano -- was still set to remain closed until July 1 at the earliest due to the ash plume. The same applied to Neuquen airport, also located in the Patagonia region.

Flights from airports across South America -- from hubs in Buenos Aires, Montevideo, the Chilean capital Santiago and southern Brazilian cities -- have all been affected in recent weeks due to clouds of ash high in the sky. The ash has also swept around the Southern Hemisphere to linger over Australasia.

The volcano, which rumbled to life early this month for the first time since 1960, is high in the Andes mountains, 870 kilometers (540 miles) south of Santiago and near the border with Argentina.

Winds have spread the ash across much of southern Argentina, hitting tourism hard at the start of the winter ski season.

As the Puyehue volcano continues to spew out ash, Chilean geologists are voicing fears of further explosions -- more bad news for air travelers, as well as local farmers who are at risk of losing their livestock and livelihoods due to the eruption.