(IDEX Online) - Botswana's mining union has issued a stark warning over the government's purchase of a 24 per cent stake in the Belgian manufacturer HB Antwerp announced last week."We should be wary to jump on a partnership with a company that is hardly two years old with no proven track record, and in the process mortgage the economy of Botswana because we were blinded by over-promises which may not be fulfilled," Kitso Phiri, executive secretary of Botswana Mineworkers Union (BMWU) told today's Sunday Times.He warned the deal could threaten the country's partnership with De Beers that dates back over half a century, although both sides have so far failed to reach agreement on renewal terms due at the end of June.Last week the country's President Mokgweetsi Masisi described the HB Antwerp deal as "the dawn of a new era for the diamond industry in Botswana".He has threatened to walk away from the deal - currently 75-25 in De Beers' favor. A Reuters' report indicated he could be demanding as much as 50 per cent, double the current allocation. As part of the deal Okavango, the state-owned diamond company, is also entering a five-year agreement to supply rough diamonds to HB Antwerp.Pic shows miners at Jwaneng Mine, Botswana