The phrase "admittedly serious" is correct and usable in written English.
It can be used when acknowledging the seriousness of a situation or topic, often to introduce a contrasting point or to soften the impact of a statement.
Example: "The situation is admittedly serious, but we must remain hopeful for a resolution."
Alternatives: "undeniably serious" or "acknowledged as serious".
Admittedly, "serious and concerned" can look quite a lot like explosive acid indigestion on some people – like Mr Le Bon here.
"Our clients are calling with concerns about the breadth of the government's reactions to what are admittedly serious transactions," said Michael L. Jamieson, a lawyer with Holland & Knight.
It perpetuates the perception that the practice is ongoing when it all stems from the one, admittedly serious, outbreak in 2011 that is still moving slowly through the system at home and abroad, both at a soccer and legal level.
That said, the BBC still is by miles the greatest broadcaster in the world, and the sight of some papers trying to trash it for two admittedly serious mistakes is fairly loathsome.
The problems of college football seemed to move from the admittedly serious to the plain hard to believe last week with the news that a major donor to the University of Miami had admitted to providing cash payments, prostitutes and lavish gifts to 72 Hurricanes players from 2002 through 2010.
There are, admittedly, serious risks of engagement efforts backfiring, particularly if communities object to engagement with particular people and organizations or if engagement partners take controversial public stances.
Admittedly Arsenal look serious challengers, but surely Beth Mead's goals will be enough to see them off?
The company's dancing has not yet become much more musically serious, admittedly, but some performers, notably Ashley Bouder and Teresa Reichlen, have made several Balanchine roles into matters of real consequence.
Take the U.S. Climate Action Partnership (US-CAP), which included three huge oil companies, and supported (with admittedly inconsistent enthusiasm) serious climate legislation.
Waterboarding, admittedly the most serious of the methods, is designed, according to Jay Bybee, to induce the perception of "suffocation and incipient panic, i.e. the perception of drowning".
Life is admittedly getting good for the most downloaded shows now that the podcasting market is getting serious attention.
