Signs of recovery began to emerge in Pakistan on Monday, but aid workers cautioned that many have yet to receive help and new threats, such as disease outbreak, are beginning to appear.

In Thatta, Pakistan, a historic southern city that was evacuated after floods inundated the area, destroying homes, schools and businesses, thousands of people began to return on Monday.

Hastily-built levees made from clay and stone held back the floodwaters, allowing many to begin to return to their homes, and others from flooded-out nearby areas to find dry land and some measure of safety.

Many of those who sought shelter in Thatta complained of a lack of assistance for thousands who had camped out in a nearby Muslim graveyard above the high-water mark.

"They throw food from the truck like animals are given food," said 75-year-old Nasima Mai, who fled with her extended family.

Matt Capobianco, a Canadian aid worker with Global Medic, said even for those who have received aid, the situation is extremely difficult in the nation overwhelmed with the scale of the disaster.

"Where we're setting up our new inflatable field hospital is right beside an adjacent hospital and the wards are just absolutely packed with patients suffering from acute watery diarrhea, and we just received word last evening that there's a possible outbreak of cholera as well," Capobianco told CTV's Canada AM on Monday.

But the sheer geographical scale of the flooding means many have not yet received any help at all, he said.

"The ones that are getting services are in a tough situation and there's a lot more that haven't been reached and are still in need of food, water, medical attention and shelter," Capobianco said.

Flooding began to hit Pakistan's northwest about a month ago after heavy monsoon rains swelled the Indus River. The swelling began to move its way south, wielding destruction along the way.

More than 1,600 people have been killed in the floods and another 17 million have been affected by flood conditions.

The post-flood reconstruction of Pakistan is expected to take years and cost billions of dollars.

International relief has trickled in over the past month, with nearly US$1 billion coming in from Muslim countries, organizations and individuals.

Millions has also come in from nations such as the U.S. and Britain, but relief has been slow compared to disasters such as the Haiti earthquake. Many observers have blamed Pakistan's poor public image and fears among donors that their money won't reach those who need it.

With files from The Associated Press