A spate of defections between Covent Garden and the rival company at the Coliseum, and dancers leaving to work overseas, are the latest troubles to hit an art under pressure

The brilliant Russian dancer Vadim Muntagirov will perform in Romeo and Juliet at the Royal Albert Hall this summer. And when the strings pick up Prokoviev's key dramatic theme – now closely associated with television's The Apprentice – Shakespeare's story of the rivalry that eventually tears apart a great city will have fresh pertinence.

It will be 23-year-old Muntagirov's last performance as lead principal dancer with the English National Ballet before he defects to the Royal Ballet. Last week the news that he had been poached by Covent Garden caused a flurry of speculation that full-scale balletic conflict would break out between London's "two households, both alike in dignity".

As the football clubs' transfer window closes this weekend, it seems there is almost as much competition going on for dance stars as there is for goal scorers. And the Royal Ballet needed an impressive signing at this stage. It had lost a succession of leading names in the last year or two, from the sudden departure of the quixotic Sergei Polunin to the loss of two admired female principals, Tamara Rojo and Alina Cojocaru, to the Coliseum – where Rojo now runs the show as the English National Ballet's artistic director. In June the accomplished principal Johan Kobborg, the boyfriend and dance partner of Cojocaru, also left Covent Garden for Bucharest, amid rumours that he had felt under-used and under-loved.

The last few days have brought further intimations of trouble at Covent Garden. One of the company's potential star performers of the future, Dawid Trzensimiech, walked out, and then the company's dancing backbone, the corps de ballet, called in union representatives from Equity to query the heavy daily workload in the rehearsal rooms that adjoin the Bow Street opera house.

Yet this weekend the Royal Ballet's artistic director, Kevin O'Hare, told the Observer that any comparison with the rivalries between the Montagues and the Capulets of Verona, or between Manchester United and Manchester City, were way off the mark. There is, he says, no ill blood between Covent Garden and the Coliseum.

Tamara Rojo and Sergei Polunin in Marguerite and Armand. Photograph: Tristram Kenton

"These movements between companies go in phases. But we see it more clearly in London, because it is a city where dancers like to stay if they can, so they might move within the country rather than go abroad," said O'Hare, who took over the top job at the Royal Ballet two years ago upon the retirement of Monica Mason. He sees increased interest in the to-ings and fro-ings between the two opera houses as a healthy sign of the popularity of ballet in Britain. "Dance is making headlines for all sorts of reasons. Whether it is because of dancers moving, or because our newly signed principal, Natalia Osipova, has won awards. There is a real interest, but there is nothing new in dancers going from one company to another."

O'Hare pointed out that the Royal Opera House's late great presiding genius, Dame Ninette de Valois, regularly expressed the hope that the dancers she trained at Covent Garden would go out later, like seeds, and create new companies on the same model around the world. Indeed Rojo, 39, has spread her wings in this manner as both artistic director and performer at the ENB after leaving the Royal Ballet. Thought to have initially wanted to be considered for the Covent Garden job that went to O'Hare, she boldly set out her stall at the Coliseum last spring. Safety and commerciality would not be priorities, the Spaniard told this newspaper.

"As some companies try to sell more tickets, they have become safer, offering more family shows like The Nutcracker and Sleeping Beauty. We forget that the one thing ballet can do is passion and overwhelming emotion," she said.

Some of the intensity of feeling surrounding the recent departures of dancers is attributable to the small size of the ballet world, argued O'Hare.

"We are like a family and lots of us have known each other since we were kids. I was at the Royal Ballet School [at White Lodge in Richmond, London] from the age of 11, and so was Vadim. So ballet is a close working environment and you always hope that people will stay part of that family for a long time. Yet you understand if they want to move."

After Muntagirov offered his services to Covent Garden, O'Hare was quick to speak to Rojo. "Vadim came to me and said he had already handed in his resignation and was interested in coming to us, so I phoned Tamara the next day. I didn't want the rumours to get around before I had spoken to her. I respect her. She was a great dancer here."

Their conversation was businesslike and polite, he said. He had not, he confirmed this weekend, approached Muntagirov first. "Vadim has had plenty of offers. He is a very humble young man, but he knows his worth. He knew he could come."

The deal was done, it seems, without the intervention of the agents that now represent top dancers, rather as sports agents represent footballers.

"I asked Vadim straight away about his contractual obligations at the ENB and he said he had Le Corsaire in Manchester, but had not been cast in anything else as far as he knew. He did want to dance Romeo and Juliet for them, though, which he will do," said O'Hare, adding that the Royal Ballet was "in a great place", riding high on a run of sellout critical successes, including the Giselle production that was broadcast in cinemas last week.

Vadim Muntagirov in Men in Motion at the Coliseum, London. Photograph: Jane Hobson/Rex

For the Observer's ballet critic, Luke Jennings, the problem is caused not by rivalry between London companies, but by the scarcity of first-rate talent. "It's an issue of supply and demand. World-class dancers are few and far between, and can afford to pick and choose. Daria Klimentova, Vadim's partner at ENB, is now 42, and may be considering retirement. They had a fantastic stage relationship, much like Nureyev and Fonteyn, but now he wants the challenges and the star roles that the Royal has to offer. Male dancers of Vadim's calibre are a very rare commodity. When one asks to join your company, you say yes."

The scarcity of dancers, some fans believe, is due to a failure in training. The Royal Ballet School expels many lower school pupils each term for failing to rack up enough of the points given out at each class. Those that survive lose the confidence and self-expression often seen in foreign dancers. The upper school then recruits dancers from an international pool for the final three years, frequently through the annual Prix de Lausanne competition.

Talking to the Observer, Muntagirov has admitted a difference in the Russian style. "I can't say it is better. Really, it is up to the taste of the audience. It is interesting for the British to see something magnificent and special, but it is the same for Russian audiences when they see dancers from London."

Ballet dancers, unlike opera singers, cannot demand vast salaries, but within a company they gain security, holiday pay and a pension. However, like opera singers, they work under great pressure and public scrutiny. Both London companies know they must build a new generation of superstars, what Rojo once described as: "Beautiful people, but with integrity too."