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The Pakistani government's record of enforcing train safety is coming under scrutiny after a fire killed more than 70 passengers.

Opposition politician Bilawal Bhutto Zadari said Sheikh Rashid Ahmed, the Minister for Railways, "has the highest record of train accidents on his watch".

Is this true? We've looked at the data.

Mr Ahmed started the job in August 2018 and between then and June 2019 there were 74 railway accidents, according to the Ministry of Railways.

As well as the recent accident, the worst in a decade, there have been several fatal accidents during this period, including a crash in July that killed at least 20 people.

What about previous years?

It's difficult to compare this period with other years because the data is incomplete. However, 74 accidents in nearly 12 months, based on the data we've seen, is not out of the ordinary.

Historical data from Pakistan Railways shows there were 757 train accidents between 2012 and 2017. That's an average of about 125 incidents a year.

Railway accidents in Pakistan

Most were caused by derailment and collisions at unmanned railway crossings.

The worst year in this period was 2015, when there were 175 incidents, of which 75 were due to derailment and 76 to collisions at crossings.

In the past six years, 150 people have died in train accidents, according to local media reports.

We've also seen separate figures provided to parliament by the Railways Ministry.

This data identifies 338 train accidents and 118 deaths in the years from 2013 to 2016.

Media playback is unsupported on your device Media caption Survivors receive treatment

Why do train accidents happen?

The government says an exploding gas cylinder used for cooking caused the blaze in this latest disaster. The fire spread through the carriages and forced many people to jump out of the moving train.

But other reports from the scene suggest electrical problems could have been the cause. Several survivors have reportedly said they believed a short-circuit on board may have been to blame.

The train was travelling between the Pakistani cities of Karachi and Rawalpindi, one of the oldest and most popular lines in the country.

Train travel is an extremely popular mode of travel in Pakistan, especially among middle and lower income groups, with tracks spanning the length and breadth of the country.

However, carriages are often overcrowded and many of the trains are in poor condition.

Also, safety inspections are more relaxed at stations than at airports, BBC Urdu's Abid Hussain says.

So banned items such as cooking stoves and oil canisters are often brought on board.

The three major causes of train accidents in Pakistan are lack of track maintenance, signal issues and older engines, according to the authorities.

Casualty figures are often high because trains are packed with far greater numbers of passengers than they were designed for.

In 2007, at least 56 people were killed and more than 120 injured in a crash near the city of Mehrabpur.

And in 2005, more than 130 people were killed when three trains collided in Sindh province in one of the country's worst train disasters.