Aziz appealed on Tuesday to foreign governments to send more money, tents, blankets and other aid to help desperate survivors four days after the 7.6-magnitude earthquake.
"The latest loss of life, the number of people dead, is approximately 23,000, injured is about 51,000," Aziz told a news conference in Islamabad.
"It is expected to rise as we go into the outlying areas."
Until Monday the government had put the casualties at 20,760 killed and 43,000 injured.
The United Nations Children's Fund and a senior Pakistani government official on Monday estimated the number of people killed in the quake at between 30,000 and 40,000.
Indian Prime Minister Manmohan Singh said the toll in Indian-administered Kashmir jumped to 1300 on Tuesday.
The quake caused massive devastation to homes, businesses, official buildings and schools across a large swathe of Pakistani-controlled Kashmir and the North West Frontier Province.
"There is one estimate of 2.5 million people will need new housing," he added.
"Whole cities have been annihilated."
Pakistan has appealed for more transport helicopters to get relief supplies to far-flung mountain villages that were flattened by landslides in the quake.
Military spokesman Major General Shaukat Sultan said the United States is to send 24 more Chinook heavy lift helicopters to Pakistan.
The US will send 24 Chinook
helicopters to Pakistan
The US military in Afghanistan sent five Chinooks and three Black Hawk helicopters on Monday and the new aircraft are expected next week, Sultan said.
"Twenty-four more Chinooks are being mobilised by the US," Sultan said.
"I think we are expecting them to arrive in one week's time."
Two German helicopters and four Afghan helicopters were also due to arrive in Pakistan in coming days, Sultan added.
Sultan said 34 Pakistani military helicopters were involved in the relief effort, although they were grounded for two hours on Tuesday because of torrential rains.
Oxfam media spokesperson Shaista Aziz, who had travelled to the capital of Pakistan-administered Kashmir, Muzaffarabad, on Tuesday, said 90% of the homes in the city had been destroyed.
"The first thing that hits you is the smell of death and the houses completely demolished," she said.
A woman receives food in
The rain had made conditions worse for survivors, some of whom had gathered in a central park, among them many women. The women said they were being left at the back of aid queues as they were not strong enough to compete with the men.
Some more remote areas are yet to be identified as in need of aid and assessed.
The start of winter on 15 October, and with snow possible, is a further concern.
"But the people are very dignified, calm and welcoming. It sums up the people of Pakistan, especially from this area," added Aziz.
Aziz's journey back from Muzaffarabad was lengthened due to the large number of Pakistanis driving to the affected areas to give blankets and supplies.
The smell of death hangs in the
air in Muzaffarabad
"The aid effort is working but only if it is planned properly," she said.
Oxfam is due to receive a joint aid flight in conjunction with Islamic Relief early on Wednesday morning.
Malaria and other diseases are breaking out in Pakistani Kashmir where health services are in ruins after the earthquake wrecked hospitals and killed many doctors, a senior health official said on Tuesday.
Corpses and sewage had contaminated the river Neelum, the main source of drinking water in the provincial capital Muzaffarabad, officials said.
"The latest loss of life, the number of people dead, is approximately 23,000, injured is about 51,000"
Pakistani prime minister
"Health services have totally collapsed here and malaria, gastroenteritis and water-borne diseases have already spread in worst-hit areas of the city," Khawaja Shabir, provincial director-general of health, said.
"We can't fight with nature, but the ground reality is very harsh - whatever water is available in the city is not fit for human consumption," he said.
He added the situation was only likely to worsen because of the polluted water and the many dead bodies still stuck under buildings that collapsed in Saturday's 7.6 magnitude quake.
The United Nations warned of risks of cholera and pneumonia.
UN officials said as many as one million people had been left homeless. They said two million children were among perhaps four million affected by the disaster.
The World Health Organisation (WHO) said in a statement that a massive health relief effort was needed and would be part of a UN appeal being launched on Tuesday in Geneva.
The UN and WHO are warning of
"We need to coordinate a massive health relief effort to ensure people get urgent care and to prevent a bad situation getting even worse," said Alan Alwan, the WHO's newly named representative for health action in crises.
Shabir said he had been in contact with the WHO and the government, and plans to avert a major health crisis were being drawn. Despite this, he said the situation was likely to worsen.
"We are making a disaster management plan for the immediate removal of all dead bodies, aerial spray on all the affected areas, but we need logistics immediately," he said.