The US State Department said more than 55 countries had offered some kind of assistance so far, including Iran and North Korea, dubbed in 2003 as part of an ''axis of evil'' by the Bush administration.
Iran's Foreign Ministry spokesman Hamid Reza Asefi said in a news conference on Sunday that ''if Iran's help is needed and requested, we would respond to the call".
Tehran's relations with the US have grown increasingly frayed over its uranium enrichment activities, but it offered the olive branch on Sunday through the Red Crescent aid agency.
North Korea's Red Cross agency stated on Saturday that it had sent a message to its US counterpart, expressing sympathy and offering to help the affected area "return to normal as soon as possible''.
"If Iran's help is needed and requested we'd respond to the call"
Hamid Reza Asefi, spokesman,
Iranian Foreign Ministry
Latin American countries Cuba and Venuzuela - involved with ongoing and recent rows with Washington - also offered to send cheap fuel, humanitarian aid and relief workers to the US Gulf Coast.
Cuban President Fidel Castro offered to fly over a thousand doctors to Houston, Texas, with 26 tonnes of medicine, where some of the flood victims have been recieving treatment, Cuban state media reported.
Meanwhile, US ally Israel said it would send a medical team to help the flood victims. Israeli Prime Minister Ariel Sharon said "we will do all that we can to help with this difficult situation that many had been caught in".
Palestinian President Mahmoud Abbas expressed great sadness at the unfolding situation and sent a consolation telegraph to US President George Bush, stating his belief in America's "capacity to overcome this disaster" and pledging Palestinian support.
Cuban President Fidel Castro
offered 1000 doctors
Iraq and Afghanistan also announced offers of assitance, with Kabul pledging up to $100,000 on Sunday, President Hamid Karzai's office announced.
Iraqi Prime Minster Ibrahim al-Jaafari offered ''material support'', the Foreign Ministry said in response to a press question earlier in the week. But there were no details of the assistance.
Saudi Arabian state owned oil company Saudi Aramco said it would be donating $5 million through its Houston based subsidiary to aid the US recovery.
Neighbouring gulf state Qatar pledged $100 million, according to the official Qatar News Agency.