Mickey Arison, chief of US cruise line company Carnival, has urged investors in UK rival P&O Princess to postpone voting on a merger which could create a $7bn giant.

Adjourning the vote would give Princess shareholders more time to consider rejecting their proposed merger partner, Royal Caribbean, and accepting an alternative $3.8bn takeover offer from Carnival instead.

"We continue to believe that Carnival's increased offer is superior to the Royal Caribbean proposal, and urge shareholders to support an adjournment of the (vote)," Mr Arison said.

The outcome of the shareholder meeting is due to be announced at 1800 GMT.

Walkout threat

Royal Caribbean has warned that a delay may prompt it to walk away from the negotiating table.

"I want to be very clear - if there is no approval of the P&O/Royal Caribbean combination... there will, for any number of reasons, be no deals," Royal Caribbean chairman and chief executive Richard Fain said.

The Princess/Royal Caribbean merger would create the world's biggest cruise liner operation, knocking Carnival off the top spot.

Princess directors have urged shareholders to back the proposed tie-up with Royal Caribbean, arguing that a merger with Carnival would be more likely to run into regulatory obstacles in Europe and the US.

They have also suggested that Carnival's tenacity in pursuing the hostile takeover stems more from its wish to scupper the Royal Caribbean/Princess merger and retain its top spot than from any real desire to buy Princess.

Shareholder split

But Carnival's offer has tempted some Princess investors, with one formally proposing a motion for an adjournment at the start of Thursday's meeting.

Supporters of a delay say final approval of the Royal Caribbean deal should wait until competition watchdogs have decided whether or not there are grounds for blocking either deal.

They believe that Royal Caribbean is unlikely to carry out its threat to pull out of the merger agreement if the adjournment motion is carried.

Voting targets

Securing an adjournment would require the backing of investors holding a simple majority of Princess shares.

Carnival on Monday claimed holders of 29% of P&O stock plan to vote for an delay.

To pursue the Royal Caribbean tie-up, P&O would need the backing of 75% of shareholders who vote.

Royal Caribbean shareholders are also set to vote on the deal at a meeting in Miami.

The P&O tie-up has already won backing of holders of 44.5% of Royal Caribbean shares.