Mark McCall has been under pressure in recent weeks

Ulster Rugby announced that McCall's three-and-a-half year tenure had come to an end at a press conference at Ravenhill on Tuesday morning.

Speculation about McCall's departure had been rife since his side lost 32-14 at home to Gloucester in Friday night's opening Heineken Cup Pool game.

The coach failed to attend a post-match media conference after his side's fifth competitive defeat in seven matches.

Ulster began their Magners League season with a home win over the Ospreys but this was followed by morale-sapping away defeats at the hands of Edinburgh, the Dragons and the Scarlets.

A spirited second-half display against Leinster earned a home draw but a further heavy loss in Glasgow heightened the pressure on the embattled Ulster coach.

The Irish province conceded five tries in a lacklustre first half performance against Guinness Premiership leaders Gloucester, effectively ending their hopes of qualification after one game.

Ulster chief executive Michael Reid said the Professional Team Managament Committee had accepted McCall's resignation on Monday night "with regret".

"The poor results this season have been very difficult for us all and ultimately have brought us to where we are now," said Reid.

"Mark has been an outstanding, committed coach for Ulster, meticulous in his preparation and he endeavoured to create an environment of empowerment for the players.

"During his three years in the job, nine players received international recognition, a greater number of new caps than at any stage since the game turned professional and an achievement which was down to the hard work and player identification of Mark and Allen Clarke.

Mark McCall and Steve Williams watch the defeat by Gloucester

"His drive, passion and enthusiasm for Ulster Rugby is immense."

"The level of abuse Mark and I have received from a small section of the crowd has been unacceptable and I have felt our personal safety has been under threat.

"That is not what we want at Ulster Rugby and I hope that element stays away," he aded.

"Mark McCall took on this job at a time when there was little money available in comparison to England and France and has worked hard to deliver a competitive team on what has not been a level playing field."

McCall did not attend Tuesday's press briefing but said it had been "an absolute privilege" to be coach of the Ulster team.

"Winning the Celtic League two seasons ago was a huge highlight but now I believe the time is right for someone else to take the team forward and I would wish all concerned every success in the future."

A record of four wins and eight defeats out of 12 matches at the end of last season had put the 39-year-old's job under threat but he survived that sharp decline in form although his assistant Allen Clarke was replaced by Steve Williams in the summer.

The highlight of the Bangor man's reign was winning the Celtic League in 2006 with a dramatic 19-17 win away to the Ospreys sealing the success.

That league victory heightened expectations but, like his predecessor Alan Solomons, McCall failed to secure qualification for the Heineken Cup knockout stages.

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McCall enjoyed Schools Cup success with Bangor Grammar School in the 1980s and went on to play for his hometown club and then London Irish in the professional era before finishing his club career at Dungannon.

He won more than 50 caps for Ulster and also played for Ireland 13 times.

McCall captained Ulster during the early part of their European Cup winning campaign in 1999 until a neck injury forced him to retire prematurely from the game.

Having assisted Harry Williams at Ulster, he had been in charge of Ballynahinch for a season when Solomons brought him into the Ulster set-up as backs coach and for two years he was assistant to Matt Williams with the Ireland A squad.

He then enjoyed two years at the helm of the Ireland Under-21 team following the departure of Michael Bradley.

McCall was assistant to Solomons when the South African left to coach Northampton and saw off the challenge of Declan Kidney to land the top job in March, 2004.

He began a three-year contract on 1 July that year and played a major part in nurturing many of the province's prodigious young talents.

His competitive record as Ulster coach reads won 44, drawn three and lost 40.

Steve Williams will take temporary charge of the team while the Ulster Branch decide on a new, permanent appointment.