Image copyright AP Image caption Many shops in Indiana are putting up stickers that condemn the Religious Freedom bill

Apple's chief executive, Tim Cook, has joined other tech firms in denouncing a law passed in the US state of Indiana, which some argue could allow businesses to discriminate against gay and lesbian customers.

Governor Mike Pence signed a bill on Thursday that prevents the state from restricting a person's ability to exercise their religion.

"We are deeply disappointed in Indiana's new law," Mr Cook tweeted.

"Apple is open for everyone".

Mr Cook, who publicly acknowledged his sexuality last October, saying that he was "proud to be gay", added in another tweet: "Around the world, we strive to treat every customer the same - regardless of where they come from, how they worship or who they love."

On Wednesday, tech executives wrote to Governor Pence, urging him to veto the bill, known as the Religious Freedom Restoration Act.

Among the signatories was Marc Benioff, the boss of US tech firm Salesforce, who subsequently announced that his company was cancelling "all programs that require our customers/employees to travel to Indiana to face discrimination".

'Opening floodgates'

Civil rights campaigners across the US have come out against the bill.

The American Civil Liberties Union (ACLU) said the law was "opening the floodgates to discrimination against LGBT people".

"The timing of this legislation is important to understanding its intent: The bill was introduced as a backlash reaction to achieving marriage equality for same-sex couples in Indiana," said Jane Henegar, executive director of the ACLU of Indiana.

However Indiana's governor insisted that the bill "is not about discrimination".

"If I thought it legalised discrimination in any way in Indiana, I would have vetoed it," he said in a statement.

Nonetheless, business leaders in the state have condemned the law.

The Indiana Chamber of Commerce called the law "entirely unnecessary" and said the "reactions to it are not unexpected or unpredicted; passing the law was always going to bring the state unwanted attention".