British security group G4S said Tuesday it had ended a deal to buy Denmark-based facilities company ISS for £5.2 billion on shareholder concerns at the size of the takeover amid economic uncertainty. The shock announcement comes one day before G4S shareholders had been due to vote on whether to approve the deal, which needed 75-percent support. G4S had on October 17 announced its plans to create the world\'s largest security and facilities firm for £5.2 billion (6.1 billion euros , $8.3 billion) -- an amount that included the value of debt held by ISS. The British group had intended to sell new shares worth a total of £2.0 billion to help fund the takeover -- a move that also needed 75-percent support from G4S shareholders. \"We believe that developing our business towards an enhanced security and integrated facilities services model is the way forward in the longer term and we saw ISS as an excellent opportunity to achieve this aim,\" G4S chairman Alf Duch-Pedersen said in a statement. \"However, following the announcement of the acquisition, shareholders have raised concerns particularly over its scale and perceived complexity against the backdrop of current macro-economic uncertainty.\" G4S, which runs four prisons and is training security guards for next year\'s London Olympics, hoped to benefit from catering and cleaning services run by ISS, which is owned by private equity firms EQT and GS Capital. \"We are obviously disappointed that we have not been able to complete this transaction,\" G4S chief executive Nick Buckles said in the statement. \"However, we respect the importance of shareholders\' views and, on the basis of feedback received since the transaction was announced, we have decided not to proceed.\"