Two teenage children of the suspect in Saturday's hostage-taking at a synagogue in Texas have been released from custody without being charged, police said.

"Two teenagers, who were both detained in South Manchester, have since been released without charge," Greater Manchester Police said in a statement on Tuesday.

The pair was arrested in England as part of the investigation after alleged hostage-taker and British citizen Malik Faisal Akram was shot dead following a nearly 10-hour standoff with police on Saturday.