Iran has blocked access to social networking site Facebook ahead of June’s presidential elections, Iran’s Ilna news agency and web users say.
A web tool hailed as a significant rival to search giant Google has gone live to the public.
Yahoo is to close its personal web hosting site GeoCities later this year.
Yahoo and Google, the world’s two biggest search engines, have announced a two-week experiment that will see them share advertising space.
During the pilot, Google will be able to place ads alongside 3% of search results on Yahoo’s website.
Analysts say the move is designed to frustrate Microsoft, which has offered to buy Yahoo for $44.6bn (£22.6bn).