Kelvin MacKenzie commissioned the research

The National Broadcast Media Survey, conducted by German marketing company GfK, recorded 17.9 million listeners a week for Radio 4 between 10 March and 20 April, compared to 15.2 million for Radio 2.

The GfK survey involves 1,000 participants wearing electronic wristbands, which record everything they listen to during the survey period.

This contrasts with recent figures produced by industry's own body, Rajar, indicating 13.2 million listeners for Radio 2 and 10 million for Radio 4 during the first quarter of the year.

THE BBC'S RIVAL RATINGS Radio 4 Wristbands (GfK): 17.9m Diaries (Rajar): 10m Radio 2 Wristbands: 15.2m Diaries: 13.2m Radio 1 Wristbands: 12.7m Diaries: 10.3m Five Live Wristbands: 10.7m Diaries: 6.4m Radio 3 Wristbands: 3.8m Diaries: 2.1m Sources: Rajar/RSL (Jan-Mar 2003) and GfK (10 March - 20 April 2003)

People taking part in the Rajar survey record which stations they listen to in diaries.

GfK's six-week survey began in March this year, including the period during the build-up to and war in Iraq.

It was commissioned by former Sun editor Kelvin MacKenzie's Wireless Group, which owns TalkSport radio, and shows speech stations have higher audiences than previously thought.

Mr MacKenzie argues Rajar's policy of not recording any listening under four minutes long hits speech stations like TalkSport badly.

TalkSport was named the most popular national commercial station in the GfK survey - beating Rajar's usual leader Classic FM.

John Humphrys is one of Radio 4's well-known presenters

But BBC Radio Five Live was the top sports station overall with 10.8 million listeners a week.

GfK says its new figures are more accurate because they measure all stations, even if listeners do not know what they have tuned into. They also take listening in cars, shops and offices into account.

Rajar's managing director, Jane O'Hara, said the two research methods could not be compared.

"In the case of the GfK research the data is based on a small sample of respondents, less than one fifteenth that of Rajar; only nine stations were reported on and the GfK definition of listening is very different," she said.

OTHER STATIONS Talksport Wristbands (GfK): 8.1m Diaries (Rajar): 2.2m Classic FM Wristbands: 7.3m Diaries: 6.8m Virgin AM and FM Wristbands: 3.9m Diaries: 2.7m Sources: Rajar/RSL (Jan-Mar 2003) and GfK (10 March - 20 April 2003)

Rajar, which is jointly owned by commercial stations and the BBC, is hoping to launch a new audience measurement system this summer.

It has recently completed trials using wristwatches and pagers.

GfK also used the wristwatch system to measure TV audiences, again recording figures outside the home including offices and bars.

This method resulted in Sky News and Sky Sports 2 more than doubling the size of their weekly audiences to 16.5 million people and 8.9 million people respectively.

GfK now plans to issue its figures at the end of each month, and from September will also include 10 stations in London, where competition among stations is at its fiercest.