Nations around the world offered support and sympathy on Friday to Japan after the devastating earthquake and tsunami that shattered the northeast of the country and cost hundreds of lives.
The United Nations said that search and rescue teams from more than 45 countries were ready to head to the country if it needs help.
"More than 68 teams from more than 45 countries are on standby," Elisabeth Byrs, spokeswoman of the UN Office for the Coordination of Humanitarian Affairs (OCHA) told AFP.
The search and rescue teams mobilised under a UN disaster response network are monitoring the situation and ready to help should Japan request aid, she explained.
United Nations chief Ban Ki-moon said the world body will "do anything and everything" to help the country.The UN would provide humanitarian assistance and send risk reduction teams to the stricken areas after the 8.9 magnitude quake which sent tsunamis across the Pacific.
"Japan is one of the most generous and strongest (UN) benefactors, coming to the assistance of those in need the world over," he said.
In Washington US President Barack Obama called Japanese Prime Minister Naoto Kan to offer help, an official said.
"(First Lady) Michelle (Obama) and I send our deepest condolences to the people of Japan, particularly those who have lost loved ones in the earthquake and tsunamis," Obama said in a statement.
Although relations between Beijing and Tokyo have been strained in recent months, Chen Jianmin, head of the China Earthquake Administration, said authorities had already put relief personnel, equipment and medicine in place, "ready to depart for Japan at any time".
Premier Wen Jiabao, whose country is no stranger to major quakes, expressed his "deep sympathy" to the Japanese government and people, and offered any "necessary help" to its neighbour, the foreign ministry said.
The shock was felt as far away as Beijing, some 2,500 kilometres (1,500 miles) distant.
The European Union said it would "mobilise all appropriate assistance". Its executive arm, the European Commission, has funds to deal with emergencies and can also mobilise equipment and experts in natural disasters.
European leaders arriving at an emergency summit on the crisis in Libya said their first thoughts were with Japan.
"The first thing is to offer sympathy and condolences to the Japanese people," British Prime Minister David Cameron said.
"We have had a terrible reminder of the destructive power of nature."
French President Nicolas Sarkozy said he "wanted to express our solidarity with the Japanese people.
"I want to tell all the Japanese people that France stands with you in this terrible catastrophe... We will send rescue teams, planes, whatever is needed to help."
Australia's Deputy Prime Minister Wayne Swan said his country was ready to "assist Japan in any way at this difficult time", adding that its embassy was "urgently" contacting authorities to see if any nationals had been affected.
South Korea also expressed its sympathy and pledged "every possible support" to help neighbour Japan recover, adding that around 40 rescue workers had been put on standby to head to the quake-hit nation.
In South Asia, India conveyed sympathies and condolences to victims as well as offering assistance.
"We are saddened by the loss of life and extensive damage to property and infrastructure," the Indian foreign ministry said in a statement.
In Sri Lanka, badly hit by the 2004 tsunami, President Mahinda Rajapakse said Japan was a "very close and dear friend" and its people possessed "incredible resilience and courage" to overcome destruction.
Pakistan's Prime Minister Yousuf Raza Gilani also said his country was ready to help.