Nov 30 (Reuters) - Canadian security firm GardaWorld said on Monday it has further extended its cash offer for larger rival G4S, which has repeatedly rejected the hostile bid valuing the British company at about 3 billion pounds ($4 billion).

The offer will remain open for acceptance until Dec. 16, GardaWorld said, after earlier extending the offer until Nov. 28. It received valid acceptances of a total of 2.8 million G4S shares, or 0.17%, as at Nov. 28.

G4S, one of the world's largest private security companies, had rejected GardaWorld's sweetened 190 pence per share proposal in September, calling it "highly opportunistic."

"GardaWorld has received only 0.17% acceptances, reflecting the derisory level of the offer," G4S said in a statement, urging shareholders to take no action.

G4S also said this month that it had rejected what it termed a "highly conditional" offer from U.S. company Allied Universal at a price of 210 pence per share.

Shares in G4S were on track to gain 13% this quarter after surging 75% in the quarter ended September. They were down marginally in early trade.

"Throughout this process, we have not seen a single piece of evidence to suggest that our offer of 190p in cash is anything other than full and fair," GardaWorld Chief Executive Officer Stephan Crétier said.

($1 = 0.7496 pounds) (Reporting by Yadarisa Shabong in Bengaluru; Editing by Shounak Dasgupta and Rashmi Aich)