The television industry has more work to do to increase diversity on and off our screens, TV bosses have said.

Their assessment comes following Idris Elba's speech in Parliament on Monday in which he called for more diversity on TV, and amidst the growing row over the lack of black stars nominated at this year's Oscars.

During a debate called "How far have we come?" at a TV industry conference about diversity held at Channel 4, one broadcasting chief said that while there has been an improvement, it is too early to be "declaring victory".

Adam Crozier, CEO of ITV, said there has been good progress made by broadcasters in the short term, but used a cricket analogy to describe what stage he thinks the process is at.

"If this was a five day test match, I think we're half way through the first morning.

"It's much too early for anyone to be declaring victory. There's a lot that still needs to be done," he said.

BBC director general Tony Hall said diversity is "core" to what the BBC is about.

He told the conference: "There is loads to do. I completely agree with Adam that this is about culture change.

"Not for one moment can we rest on any laurels we might think we can rest on, in that we've just got to keep pushing."

Earlier Idris Elba spoke in Parliament about diversity in television.

The star, known for his roles in Luther and The Wire, spoke about the importance of the creative industries to the British economy and called for "imagination" and "diversity of thought".

He touched upon skin colour, gender, age, disability, sexual orientation and social background in a speech that lasted about 30 minutes and was full of witty remarks that drew laughs from the packed committee room in Westminster.

"The Britain I come from is the most successful, diverse, multicultural country on the earth.

"But here's my point: you wouldn't know it if you turned on the TV. So many of our creative decision-makers share the same background," he said.

Speaking about his own path to stardom, the 43-year-old actor said: "I'm a product of my imagination.

"Made in Hackney. Made in Newham. Made in Dagenham. But above all, I was made in my mind: I'm seeing it, thinking it, doing it."

Elba said he used to fit tyres and now he makes films in Hollywood. "And the difference between those two lives is opportunity.

"By the way, I got my tyre-fitting job through the Youth Training Scheme," he said.

The star added: "Before that, for a while I went to a disabled school because I had severe asthma.

"I finally got my first break in the creative industries from the Prince's Trust. Yes, good old Prince Charles came in there."

He said he was helped on his way into working in theatre, and from there TV and film.

"The Prince's Trust subsidised one of my first jobs with the National Music Youth Theatre. They gave me £1,500, because my parents didn't have enough money.

"There were hardly any black kids, because none of us could afford it.

"And although back then I didn't get to meet Prince Charles, we had one thing in common. We both fell into the same line of work as our parents did.

"It's true. My dad worked in a car factory, so before I could get any work as an actor, I ended up doing night shifts at Dagenham.

"In fact Ford Dagenham had more opportunity and diversity than the TV industry I was trying to break into," he said.

Elba was speaking on the eve of a major TV industry conference on diversity.

The crowd also heard from Channel 4 chief executive David Abraham about what the channel achieved in 2015 in terms of diversity.

Elba had the crowd in fits of laughter when he lightened the mood with some wit throughout his speech.

"A long time after I left school, someone explained to me what the Magna Carta was.

"Now for people in your industry, Magna Carta is the basis of modern democracy.

"And for people in the music industry, it is an album by Jay Z," he joked.

"So Magna Carta was a peace treaty between the kings and the barons. Shout out to the barons in the room," he said, provoking chuckles.

He then added: "These jokes are horrible."

Getting back to his point, he said: "In a funny way, broadcasting needs a Magna Carta.

"We need to start doing things more fairly.

"It's not so much a peace treaty; but an opportunity treaty.

"We need to count up what everybody has, see the lay of the land, and see who has which careers in TV.

"Who makes TV? Who's allowed on TV?

"And when they get the opportunity, which roles do they play, off and on screen.

"Are black people normally playing petty criminals?

"Are women always the love interest or talking about men?

"Are gay people always stereotyped?

"Are disabled people ever seen at all?

"Do some people have their careers taken away on a whim?

"Is their talent unfairly ignored?"

In conclusion, Elba said: "So my message today is, let's just get more professional about this whole area.

"Our economy depends on it. Our future actually depends on it.

"Nelson Mandela said 'Anything difficult always seems impossible until it's done'.

Elba, who played Mandela in Mandela: Long Walk To Freedom, put on the famous leader's accent for that last quote, prompting applause from the crowd.

He then joked: "I don't know how I got the job to do that."

He added: "But the good news is, we're not trying to put a man on the moon.

"We're trying to redesign the face and character of British television."

Meanwhile, Channel 4 has announced that 2016 will be the broadcaster's Year of Disability. It will make commitments to increase representation of disabled people within the broadcasting industry both on and off screen.

The channel said it will double the number of disabled people appearing in 20 of its biggest shows - with disabled contributors on programmes such as Gogglebox, The Island, Grand Designs, Hollyoaks, and First Dates.

Three hundred thousand pounds will be invested in new talent initiatives, with an off-screen commitment to progress the careers of 20 disabled people already working in the industry in Channel 4's 20 biggest suppliers.

And within the channel, 50% of all apprenticeships and 30% of all work experience placements will be ringfenced for disabled people, the broadcaster said.

Channel 4's 360 Degree Diversity Charter found that over 2015 the broadcaster had achieved 24 of the 30 targets it set itself a year ago.