Google and Yahoo have res­ponded to inquiries by the US Department of Justice’s antitrust division about an alliance they launched earlier this month that had been expected to improve Yahoo’s bargaining position with Microsoft.

Yahoo, the search company that is seeking to fend off an unsolicited $43bn takeover bid by the software giant, on Wednesday said it had “proactively” kept the DoJ informed about its intention to conduct a limited test with its rival, Google, and that it had provided the DoJ with information about the test.