Yahya related to me from Malik from Alqama ibn Abi Alqama thathis mother said, "I heard A'isha, the wife of the Prophet, may Allahbless him and grant him peace, being asked whether some one in ihramcould scratch their body or not, and she said, 'Yes, he can scratch itand do so as hard as he pleases. I would scratch even if my hands weretied and I could only use my feet.' "
USC-MSA web (English) reference: Book 20, Hadith 94
Arabic reference: Book 20, Hadith 796