Castro, 90, offers thanks on birthday, slams Obama

Fidel Castro thanked Cubans for their best wishes on his 90th birthday and criticized US President Barack Obama in a lengthy letter published by state media. He appeared but did not speak at a gala in his honor broadcast on state television.

"I want to express my deepest gratitude for the shows of respect, greetings and praise that I've received, which give me strength to reciprocate with ideas that I will send to party militants and organizations," he wrote on Saturday.

"Modern medical techniques have allowed me to scrutinize the universe," wrote Castro, who stepped down as Cuba's president 10 years ago after suffering a severe gastrointestinal illness.