They say the clots, also known as thrombosis, could be contributing to the number of people dying.
Severe inflammation in the lungs - a natural response of the body to the virus - is behind their formation.
Patients worldwide are being affected by many medical complications of the virus, some of which can be fatal.
Back in March, as coronavirus was spreading across the globe, doctors started seeing far higher rates of clots in patients admitted to hospital than they would normally expect.
And there have been other surprises, including the discovery of hundreds of micro-clots in the lungs of some patients.
The virus has also increased cases of deep vein thrombosis - blood clots usually found in the leg - which can be life-threatening when fragments break off and move up the body into the lungs, blocking blood vessels.
To add to all these medical challenges, there are studies showing that the blood thinners currently being used to treat the blood clots are not always working. And ramping up doses to much higher levels risks patients suffering major bleeding which can be fatal.
The balance between treating the thrombosis and causing bleeds is "a precarious one", according to Prof. Arya.
But there is now a big push to get medical teams from around the world to co-operate in finding the safest and most effective way of tackling the blood clot problem thrown up by the virus.
Trials are underway to find a standard dosage of blood thinners to be used in all countries.
However, some experts believe there could be another solution: finding a way to reduce the acute inflammation in the lungs which leads to the creation of sticky blood, the source of the problem.