Scottish Power and the Royal Bank of Scotland (RBS) are poised to unveil a massive joint venture to sell general insurance to the utility's five million customers.

The venture will have a name and brand of its own but these have yet to be revealed.

It will be marketed from late next month, with one source suggesting a launch date of April 26.

A Scottish Power spokeswoman said the utility planned to sell "various insurance but our first will be household insurance".

Scottish Power refused to confirm details of which insurer will be used.

However, it is believed that Green Flag, which has just been named as the company dealing with all RBS's affinity insurance business (see story page 4), looks best-placed.

The Scottish Power spokeswoman claimed the timetable for the launch has still to be finalised. She said: "We are planning to sell insurance, but we don't have an exact date yet. It's far along the line, though, and will be sooner rather than later."

Scottish Power and RBS originally announced a financial services joint venture at the start of this year. Details were not revealed at the time, but the two companies said they planned to extend the services available to Scottish Power's credit-card holders.

"We are looking at insurance to extend the offerings of our Visa card, and furthering our relationship with the Royal Bank," the spokeswoman said.

Scottish Power has issued its own Visa card for the last four years but the spokeswoman refused to divulge how many customers use it.