Marlon Harewood's controversial goal in first half injury-time plunged Birmingham into deeper relegation trouble as they crashed to a sixth defeat in seven Barclays Premiership games at St Andrews.

There was nothing wrong with Harewood's finish, but television replays suggested the ball had gone out of play before Matthew Etherington delivered his cross.

Blues deserved at least a share of the spoils on the strength of their second-half performance when they created several decent opportunities.

Emile Heskey dominated in the air and fit-again midfielder David Dunn was a constant threat throughout the 90 minutes.

But statistics show that Steve Bruce's side have lost six of their last seven league games and to add to their woes they picked up three injuries - with Mario Melchiot, Muzzy Izzet and Martin Taylor the unlucky men.

West Ham will be delighted to have cracked the 20-point barrier before Christmas in their first season back in the top-flight as they registered their first away win since mid-September.

They looked a threat on the break in the first half via Harewood and Bobby Zamora but were left hanging on in the final 45 minutes which was virtually one-way traffic towards their goal.

Blues defender Melchiot, who has only just returned to action after a six-week lay-off with knee trouble, lasted only eight minutes before limping off with a similar problem to be replaced by Stan Lazaridis.

Birmingham shrugged aside the setback and went ahead in the 11th minute through Heskey's fourth goal of the campaign, but the creator was fit again David Dunn.

The former England Under-21 captain, in his first home start in a year, took advantage of Yossi Benayoun losing possession and slotted an inch-perfect pass into the path of Heskey.

He calmly took the ball in his stride, evaded the challenge of onrushing goalkeeper Roy Carroll and slotted his low shot home from a narrow angle.

West Ham retaliated and Harewood was then only just too high with a drive from the edge of the penalty area after Nico Vaesen had elected to punch clear another Etherington corner.

Harewood's looping header from Benayoun's right-wing cross was tipped onto the crossbar by Vaesen before Blues suffered a second injury after 22 minutes when Izzet appeared to damage his hamstring and made way for Nicky Butt.

Tomas Repka was yellow-carded by referee Martin Atkinson just after the half-hour mark for handball to prevent the impressive Dunn from having a run at goal.

Then after 36 minutes Zamora brought West Ham back on level terms with a superb individual goal.

He latched onto a throw from Harewood and held off challenges from Lazaridis, Martin Taylor and Damien Johnson before netting from a narrow angle - his fourth goal of the season in all competitions.

Then in injury-time West Ham went in front in through Harewood.

Etherington's low cross took an unintended deflection across goal off Benayoun and Harewood hammered the ball into the roof of the net at the far post.

Birmingham were forced into their third substitution for the second half when Neil Kilkenny came on for Martin Taylor who had picked up a knock.

Dunn went close when he cut in from the left and fired a low curling drive into the side-netting.

Carroll had problems dealing with an up-and-under from Johnson but Butt's control let him down when the ball broke to him in space on the edge of the area.

West Ham retaliated and Vaesen went down to his left to cling onto a low Harewood drive after a well-worked free-kick.

The home side were in the ascendancy and Butt volleyed over from 12 yards out with Heskey creating the opening after challenging for Pennant's cross.

Dunn's cross-shot clipped the outside of the post with Carroll well beaten and Matthew Upson blazed wide from close range.

Teams

Birmingham Vaesen, Melchiot (Lazaridis 8), Cunningham, Martin Taylor (Kilkenny 45), Upson, Pennant, Johnson, Izzet (Butt 23), Gray, Dunn, Heskey.

Subs Not Used: Maik Taylor, Jarosik.

Booked: Heskey.

Goals: Heskey 11.

West Ham Carroll, Repka, Gabbidon, Ferdinand, Konchesky, Benayoun (Newton 90), Noble (Dailly 78), Mullins, Etherington, Harewood, Zamora (Bellion 69).

Subs Not Used: Hislop, Clarke.

Booked: Repka.

Goals: Zamora 36, Harewood 45.

Att: 24,010

Ref: M Atkinson (W Yorkshire).