"high-level representatives" is correct and usable in written English.
You can use it when you are referring to individuals who are part of a delegation that is at a higher level than other representatives. For example, "High-level representatives from the American and Canadian governments met to discuss trade agreements."
On the Ukrainian side, we were met by some high-level representatives of the [self-proclaimed] Donetsk People's Republic.
Between June and August, Hurley resumed protracted discussions, both indirect and in conferences with high-level representatives from both sides.
"However, there is a silver lining here – the administration has appointed high-level representatives to pursue a global solution for aviation and climate," WWF said.
It appeared likely that talks between high-level representatives of the unions and Verizon would continue through the night and perhaps longer, regardless of what midlevel union negotiators did at midnight, people close to the talks said.
Today I am announcing the dispatch of high-level representatives to allied capitals in Europe, Asia, Australia and Canada to discuss our common responsibility to create a new framework for security and stability that reflects the world of today.
The trickle of narrowly focused, functional meetings from the early 1950s became a torrent in the 1990s with a series of widely publicized gatherings attended by high-level representatives and several thousands of other participants.
The White House believes it erred in failing to send a high-level representative to the Unity rally in Paris on Sunday attended by Cameron and other EU leaders.
Obama's pivot comes two weeks after the White House faced criticism for not sending a high-level representative to Paris for a peace rally in the wake of terrorist attacks there.
But while those decisions will have been shaped by commercial considerations, UN goodwill ambassadors are appointed on the basis that they are "persons of integrity" who "possess the personality and dignity required for such high-level representative capacity".
Mr. Annan told Mr. Shah there was no longer a need for a high-level representative for Iraq, where the United Nations has no arms inspectors and is largely limited to aiding the "oil for food" program.
Former UN secretary-general Kofi Annan was appointed to serve as the high-level representative of the secretaries-general of the UN and the League of Arab States for the Syrian crisis.
