Shares in UK broadcasters Granada and Carlton have received a welcome boost on news that they are planning to combine their programme and marketing activities.

Granada shares closed up 12% at 84 pence while Carlton rose 9% to 140.75p.

The two companies said on Monday that they would work closely together on programme scheduling and marketing to increase their advertising income and number of viewers.

Carlton chief executive Gerry Murphy told the Financial Times newspaper that the joint approach would result in a "virtual enterprise", to be launched in the autumn.

The two firms are the biggest franchise holders of the ITV television network, but have been hit hard by the slump in advertising revenue during the past year.

'Virtual enterprise'

Earlier this year Granada and Carlton explored a full-blown merger, but abandoned the plan when it became clear that regulatory approval was unlikely.

"Under current competition rules a full merger would be very difficult", a Carlton spokesman said.

"This is an initiative to make ITV more competitive, to improve its efficiency and marketing."

The two media firms hope to co-ordinate their programme scheduling, and make joint approaches to advertisers.

They want to "make the most of marketing ITV to advertisers... in a multi-channel environment," the spokesman said.

Although both firms will still act as separate companies, they will combine back office operations.

Scottish takeover talks

Carlton currently operates five regional ITV franchises, including HTV and Central, while Granada has seven licences, Anglia, Meridian, Granada, Yorkshire, Tyne Tees, Border and LWT.

Earlier this year, another Carlton and Granada collaboration suffered a spectacular failure, when the pay-TV firm ITV Digital collapsed and went into liquidation.

In June both firms bought a controlling stake in the faltering ITN news channel, which is operated by the company that supplies ITV, Channel 4 and Channel 5 with news.

Both firms are currently rumoured to be in talks with Scottish Media Group about buying the television franchises Grampian and Scottish TV.