By Beatrice Murail BBC News Online

The train crash in the Dodoma region of Tanzania is the latest in a series of rail accidents in Africa over the past few years.

Technical problems, human error and negligence have all played their part in the collisions and derailments.

South Africa has tried to improve safety standards

Last month, about 200 people died and hundreds more were injured in Mozambique when a driver used four large stones to stop the carriages of his train from rolling downhill after his engine lost power. But the makeshift brakes gave way.

In what is believed to have been Malawi's worst rail disaster in May 1998, 23 people died and more than 160 were injured when the brakes of a train - and its coaches - failed on a bend. Negligence was blamed.

Many of Africa's train crashes happen in South Africa, which has the heaviest rail traffic on the continent.

A human signalling error was believed to have been the cause of a train crash in South Africa in November 2000, in which four people were killed.

And the theft of cables used in signalling systems led to a train crash in which 22 people died and at least 10 were injured in South Africa in February 2002.

Safety standards

The worst rail crash in South Africa took place in 1994, when 67 people were killed in a derailment.

In March this year, the country's Transport Minister, Dullah Omar, introduced an Independent Rail Safety Regulator Bill aimed at harmonising safety standards.

Every year, South Africa hosts a conference on the development of African railways.

In Morocco's worst rail disaster, in 1993, a train carrying naphtha, a mixture of hydrocarbons, exploded as it rammed a passenger train, killing scores of people.

And in Nigeria in December 1999, 12 people died when a train hit a truck carrying women farmers across railway tracks.

One of the most deadly rail crashes on the continent occurred outside Yaounde, Cameroon, in February 1998, when a train carrying oil derailed and exploded.

About 100 people were killed - many had been trying to scoop up leaking oil.

Despite the human factor, some rail crashes have been blamed on nature.

In Kenya in 1993, 114 people perished when a train plunged into a river after floods washed a bridge away.