Twitter has bought 900 patents and signed a cross-licensing agreement with IBM, bulking up on its intellectual property portfolio. The deal was signed up in December, but the two companies announced it on Friday.

Financial terms were not disclosed.

The agreement comes after Big Blue accused Twitter in November of infringing three of its patents.

Facebook had faced similar claims before its own 2012 IPO and has also acquired intellectual property from Microsoft and IBM.

"This acquisition of patents from IBM and licensing agreement provide us with greater intellectual property protection and give us freedom of action to innovate on behalf of all those who use our service," Ben Lee, Twitter's legal director, said in a joint statement with IBM on Friday.