Around 20 workers of mining giant De Beers travelling in a bus have been killed after a collision with a lorry in South Africa on Sunday, said the officials.20 mining workers killed in bus-lorry collision incident in South AfricaThe bus involved was ferrying staff from the Venetia mine, which is one of the biggest diamond mines in the country, said a transport official in Limpopo province, in the north of South Africa.Briefing about the incident, official Vongani Chauke said, “The bus came into collision with a lorry.”The road accident happened at around 1600 GMT, some 25 kilometres (15 miles) from the mine, at the village of Musian on the border with Zimbabwe, he said.However, the cause of the accident has yet not been established.Notably, South Africa has been one of the most developed road networks on the continent. But ironically, it also holds one of the worst road safety records.About De Beers GroupThe Venetia mine, which lies near the borders with Botswana and Zimbabwe, has been run by the De Beers Group for over 30 years.This mining giant accounts for over 40 per cent of the countrys annual diamond production, employing more than 4,300 staff including many locals.Once it was the largest open-cast mine in South Africa, before De Beers invested $2 billion in a major underground project to access the less easily available diamonds. The group aims to produce four million carats a year.In July, De Beers announced the start of underground diamond production from the new seams opened underneath the open-cast mine.