Security firm G4S Plc has pulled the plug on its planned 5.2 billion pounds acquisition of Denmark's ISS after failing to secure shareholder support.

Shareholders have raised concerns particularly over its scale and perceived complexity against the backdrop of current macro-economic uncertainty, G4S chairman Alf Duch-Pedersen said in a statement.

The company also said its planned 2 billion pound rights issue to fund the acquisition had been scrapped.

G4S, which is the world's biggest security firm, said it had cancelled a shareholders meeting for Wednesday to seek approval for both the acquisition and rights issue.

The company faced a backlash from shareholders who had objected to the strategy and financing behind the deal.

Aside from balking at the size of the rights issue - the biggest equity fundraising in Britain since a 3.4 billion pound cash call by Standard Chartered last November - shareholders raised concerns over G4S moving away from its security services roots into areas such as cleaning and catering.

Chief Executive Nick Buckles held frantic meetings to try to bring investors on side but was unable to secure the support needed to push the deal through.

We respect the importance of shareholders' views and, on the basis of feed-back received since the transaction was announced, we have decided not to proceed, Buckles said on Tuesday.

G4S had required 75 percent shareholder approval to proceed with its plans.

(Reporting by Matt Scuffham; editing by Rhys Jones and David Cowell)