The Inter-Services Public Relations (ISPR) announced on Wednesday that the main ceremony to commemorate Defence and Martyrs Day at the military's General Headquarters (GHQ) on September 6 has been postponed.

In a Twitter post, the military's media wing said that the decision was taken in "solidarity with the flood-affected people of Pakistan."

The statement added that "Pakistan Armed Forces shall continue serving our brothers and sisters struck by unprecedented floods."

Floods caused by record-breaking torrential rains have devastated the north and south of the country, affecting over 33 million while causing large-scale infrastructural damage.

The millions of people affected by the floods face major health hazards including potentially deadly diseases such as malaria and dengue fever, the WHO warned in a statement Tuesday.

Sindh province, in Pakistan's south, has been hit particularly hard, with vast swathes of land under water and many villagers forced to head to large cities for shelter, food aid, and medical assistance.

Flood emergency: UN announces flash appeal for $160m to assist Pakistan

On Wednesday, United Nations Secretary-General Antonio Guterres announced a flash appeal for $160 million to support the Pakistan government's flood relief efforts.

Speaking at an event hosted by Pakistan's Ministry of Foreign Affairs (MOFA), he said “these funds will provide 5.2 million people with food, water, sanitation, emergency education, protection, and health support.”

The rains that began in June have unleashed the worst flooding in more than a decade, washing away swathes of vital crops and damaging or destroying more than a million homes.

Authorities and charities are struggling to accelerate aid delivery to more than 33 million people affected, a challenging task in areas cut off because roads and bridges have been washed away.