No signs of biological and radiological material were encountered in the suspicious letters that were sent to the Ankara Courthouse on Monday, said the province's governorate.

The 6th High Criminal Court in Ankara received two suspicious letters containing yellow powder on Monday morning.

"The two letters do not contain any biological and radiological substance," the Governorate said following examinations conducted by Turkey's emergency and disaster agency, AFAD.

Since Friday, letters containing a suspicious yellow substance were delivered to Canadian, German, Hungarian, Belgian, French and American consulates in Istanbul.

Earlier Monday, the Turkish Health Ministry announced that no signs of biological warfare material were found in the suspicious letters.