Heavy monsoon rains have wreaked havoc in Pakistan, killing at least 28 people, including women and children, and triggering flash floods and landslides in several parts of the country, officials said on Sunday.

At least 12 people were killed and over 22 others injured in different parts of Khyber Pakhtunkhwa due to flash floods, landslides and rain-related accidents, said a spokesman for the Provincial Disaster Management Authority (PDMA).

Three people were killed each in Bajaur and Swat district. One person was killed each in Dir Lower, Buner, Malakand, Shangla, Aurakzai and Torghar districts, the spokesman said, adding that the deceased included two women and two children.

In Chitral district, the colony setup for Chinese engineers working on Lawari tunnel was also inundated by flash floods, the official said.

However, the engineers were evacuated to safer places.

At least six people were killed when their vehicle fell in the Indus river in Kohistan district.

The passengers were travelling from Gilgit to lower dir district for Eid vacations when they met the accident took place at Janchal area.

Torrential rains in Karachi since late Saturday have killed around 10 people and caused widespread damage and heavy flooding on roads and in neighborhoods, an official said.

The heavy monsoon showers for the second day also caused widespread electricity breakdown in half of Karachi.

According to the Pakistan Meteorological Department (PMD), a total of 150 millimetres of rain has been recorded in Karachi so far and there is forecast for more rain for Sunday night.

"These are the heaviest monsoon rains in Karachi since 1992 due to heavy cover over the Arabian sea but it will pass by Monday," Hanif Rajput an official of the PMD said.

Local news channels reported that a dozen sacrificial animals brought by cattle traders for Eid ul Azha to be celebrated on Monday were also killed electrocuted.

"There has been heavy flooding in many residential areas of the city especially the low laying neighborhoods," said Sindh minister for local bodies

Nasir Shah.

Even in the red zone security and posh areas of Defence Housing Society and Clifton and near the Governor House and Chief Minister's house, the roads were flooded and several cars were seen stranded in water.

Officials said that highways from Karachi to interior Sindh and Baluchistan were also affected by the heavy rains and at some places closed down to clear the flooded roads.

Karachi-Electric, in a tweet, said that the rainfall had created a "critical situation in Karachi" and urged the city administration to declare a state of emergency.

Rains and snowfall often cause landslides and flash floods in northern Pakistan where millions live in mountainous areas.

Last month, at least 28 people were killed in heavy rains and flash floods that wreaked havoc in the Neelum Valley in Pakistan-occupied Kashmir.