International rescuers on Monday were battling heat and fatigue to look for any survivors still trapped under the rubble in Port-au-Prince six days after the earthquake in Haiti, and doctors were going all out to treat the injured.

The Chinese medical team worked around the clock at the assistance station set up at the Haitian prime minister's residence, giving treatment as well as medical service to local victims. They also handed out medicines and sterilized areas surrounding temporary tents.

Officials said about 280 assistance centers have been set up in schools, churches and public buildings in Port-au-Prince and its six nearby towns. The centers handed out disaster-relief materials and can accommodate about 500 people each.

An official from Brazil said violence for foods was declining since drinking water and food began to be distributed to the victims.

According to the United Nations, the number of Haitians affected by the earthquake could exceed 3 million.

Bolivian Vice President Alvaro Garcia traveled on Monday to Port-au-Prince aboard a military plane with 50 tons of humanitarian aid, including food, medicine, blood and plasma. President Evo Morales pledged more medicine and food from Bolivia.

The Brazilian Air Force announced on Monday that another plane full of supplies took off from Rio de Janeiro for Port-au-Prince. The Boeing 707 carried 14.8 tons of food. So far, 14 Air Force planes have left Brazil carrying supplies to Haiti.

European Union (EU) institutions and member states pledged over 400 million euros (about 572 million U.S. dollars) in aid to Haiti, an EU official said Monday.

The European Commission pledged 30 million euros and EU member states offered a total of 92 million euros in immediate emergency aid to Haiti, said EU Development and Humanitarian Aid Commissioner Karel De Gucht.

EU institutions will provide an extra 100 million euros in "early rehabilitation" aid, and a further 200 million euros for the medium- and long-term reconstruction in the country.

The British government is trebling the amount of aid being provided to Haiti, the prime minister's office announced on Monday. The total sum will rise from 6.1 million pounds (10 million dollars) announced on Thursday to 18.4 million pounds (30 million dollars).

The Swedish government said it would disburse its entire annual contribution of 425 million Swedish kronor (about 67 million dollars) to the UN Central Emergency Response Fund (CERF) for quake relief in Haiti.

France decided Monday to provide 10 million euros (14.3 million dollars) in response to a UN call, the country's Foreign Minister Bernard Kouchner said in a statement. With the new pledge, France's assistance to Haiti amounted to around 20 million euros (28.6 million dollars), according to a government statement.

In China, private donations for quake victims in Haiti have reached 1.73 million yuan (253,280 dollars) as of Monday, according to the Red Cross Society of China (RCSC).

Wang Xiaohua, a liaison director of the RCSC, said the donations were made by enterprises, individuals and local branches of the RCSC. The largest donation from a single individual stood at 50,000 yuan.

In Haiti, humanitarian organizations are busy helping the local people quickly develop self-assistance capabilities.

In response to the inaccessibility of potable water, CARE International began to give water purification training on Monday. It has distributed 600,000 water purification tablets and is teaching locals how to use them.

"CARE staff train local volunteers, so they can teach others and distribute the packets according to a careful inventory of families at the site to be sure it reaches those most in need," Dr. Franck Geneus, coordinator of CARE's health program in Haiti, said in a statement.

The World Health Organization (WHO) said Haiti's public health failures had impaired the earthquake relief effort.

According to the WHO's public health risk assessment on Haiti, the likelihood of infection and tetanus resulting from trauma wounds is high, as vaccination rates are minimal.

WHO Director-General Dr. Margaret Chan said Haiti was marked by "diseases associated with poor sanitation systems, low immunization coverage and widespread malnutrition, outbreaks of infectious diseases, a high prevalence of HIV/AIDS and tuberculosis, and erratic delivery of medicines and care."

The WHO hopes to address these concerns with mass vaccinations for measles and tetanus, as well as increased access to care.

Amid concerns that security could deteriorate further, roughly 400 UN police and military troops have been brought into Haiti's capital from around the country.

For the time being, security remains under control in the quake-ravished nation, the chief of UN peacekeeping operations, Alain LeRoy, told reporters, but there have been "sporadic incidents" due to Haitians becoming frustrated by sluggish relief efforts.