Emotions will be running high in EastEnders next week as Mark Fowler - played by Todd Carty - lies critical in hospital with pneumonia.

In Monday night's episode, fans of the BBC soap will see Mark fighting for his life as the illness makes him progressively weaker and unable to breathe.

At his bedside, his mother Pauline Fowler, played by Wendy Richards, will keep a constant vigil after being told that the next 24 hours will decide whether her son lives or dies.

Mark - who is HIV positive but not taking his prescribed drugs - was last seen in Thursday night's episode collapsing onto the floor of his kitchen.

'Progressive illness'

Over the last few weeks, he has been complaining of feeling unwell.

A spokeswoman for the programme said: "HIV is a progressive illness and Mark is experiencing what other sufferers go through as the disease takes its toll.

"The reason this attack of pneumonia is so severe is that Mark has not been taking his combination pills.

"He recently decided to stop taking them because he could not cope with the side-effects."

Also watching anxiously for signs of improvement will be Mark's friend Lisa Shaw, played by Lucy Benjamin.

Market trader Mark collapsed after a tearful scene with former flatmate Lisa as he begged her not to leave him to live with Melanie Healy, played by Tamzin Outhwaite.

In a previous episode, Mark had told Lisa - who is the girlfriend of Phil Mitchell, played by Steve McFadden - that he was in love with her. But, she eventually decided to move out after relations between them had become increasingly strained.

Developing storyline

Mark is thought to have contracted the HIV virus from his first wife Gill who was infected by a drug dealing ex-boyfriend. Gill died the day after she married Mark in hospital.

Over the past few years, Mark has been shown coping with his HIV. He has managed to keep it under control with various different drugs and received regular counselling to help combat the illness.

Todd Carty made his name as a boy playing the character of Tucker in the original cast of the popular Children's BBC programme Grange Hill.

As a teenager, he went on to star in his own off-shoot drama series Tucker's Luck before joining the cast of EastEnders in 1985.

Since his character Mark was diagnosed as HIV positive, a number of storylines have been written around the issue.

Most notably, Mark was seen having to deal with a wide range of reactions to his illness, some hostile, from other Albert Square residents.

Another emotional storyline revolved around his second wife Ruth's dilemma over wanting children but eventually having to give the idea up.