The United States and Europe vowed to come to Chile's aid as relief workers rushed to the Western hemisphere's second enormous earthquake in seven weeks.
But the Latin American country, reeling from the deaths of at least 300 people and a trail of destruction caused by Saturday's 8.8-magnitude quake, appealed for foreign donors to wait until the scale of the task is clear.
"We are very grateful for people's good intentions, but let's let the (Chilean) emergency office get its very specific report on needs done," Foreign Minister Mariano Fernandez told reporters.
Chile does not want "aid from anywhere to be a distraction" from disaster relief, he said. "Any aid that arrives without having been determined to be needed really helps very little."
At least 1.5 million homes were damaged in the pre-dawn quake, roads were torn up and buildings reduced to rubble in the nation of 16 million people. The main international airport in the capital Santiago suffered heavy damage.
Much of Santiago was plunged into darkness. The country's second largest city, Concepcion, south of the capital, was near the epicenter of one of the largest quakes on record.
"We anticipate the situation in the worst-affected areas closer to the epicentre to be much more serious," said Pete Garratt, the disaster relief manager for Britain's Red Cross.
"Our fear is that this quake will have had large-scale impact."
UN chief Ban Ki-moon is "very closely monitoring developments, including the risk of Pacific Rim tsunamis, after the huge earthquake in Chile," his office said. A Pacific-wide tsunami alert was lifted, but Japan and Russia were still braced for super-sized waves.
US President Barack Obama pledged to meet any request for help from Chile, while the European Union offered three million euros (four million dollars) in immediate aid.
The United States "stands ready to assist in the rescue and recovery efforts, and we have resources that are positioned to deploy should the Chilean government ask for our help", Obama said in a televised address.
Spain, which holds the EU's rotating six-month presidency, offered to help coordinate relief efforts once the damage and requirements are assessed.
The Madrid government said it was "prepared to offer, as in the case of Haiti, all its available capabilities in the region to provide a coordinated response to this new disaster that has rocked a friendly and brother country".
Unlike impoverished Haiti, which was pulverized by an earthquake last month, Chile is one of Latin America's wealthiest countries.
Nevertheless international aid charities said they were dispatching experts to Chile but predicted that the devastation would be far lower than in Haiti, where the January 12 quake killed 200,000 people.
British charity Oxfam said it was sending five water engineers and logistics experts from Chile to Colombia.
Disaster relief charity ShelterBox said it was mobilising an initial response team from Britain and the United States, and the Swiss government said it too was deploying an assessment team to Chile.
The US group Mobile Giving Foundation enlarged a cellphone donation drive that has so far raised 41 million dollars for Haiti.
By texting the word "Chile" to a five-digit phone number, Americans and Canadians can give five or 10 dollars to groups including Habitat for Humanity, the Salvation Army or World Vision, it said.
European Commission chief Jose Manuel Barroso announced in Brussels that the EU's executive arm was sending three million euros in fast-track aid to Chile.
"I am deeply shocked at the extent of the devastation that is emerging," Barroso said, as European leaders joined Obama in sending heart-felt condolences and offers of assistance to Chile.
"The people of Chile are in agony today but Britain stands ready to help. We will do whatever we can," said British Prime Minister Gordon Brown, while French President Nicolas Sarkozy expressed his "deep emotion".
The World Bank said it stood ready to "draw on its considerable expertise in catastrophe management and reconstruction" to support Chile.