Image caption Prosecutors say Dias Kadyrbayev, left, and Azamat Tazhayakov realised their friend resembled suspect photos

Three college friends of the Boston bombings suspect have appeared in court, accused of obstructing the police investigation into the attacks.

Azamat Tazhayakov and Dias Kadyrbayev - both from Kazakhstan - threw away Dzhokhar Tsarnaev's laptop and backpack, police say.

Robel Phillipos is accused of lying to investigators. None of the three is implicated in plotting the attacks.

Three people died and 264 were wounded in the 15 April marathon blasts.

Mr Tsarnaev, a 19-year-old student, has been charged over the bombings. His 26-year-old brother, Tamerlan, was killed during a shootout with police.

'Risk of flight'

The three 19-year-olds accused of hindering police investigators appeared in Boston federal court on Wednesday.

Mr Tazhayakov and Mr Kadyrbayev are charged with destroying evidence.

Image caption The FBI says they found these fireworks inside a backpack belonging to Dzhokhar Tsarnaev

Mr Phillipos, a US citizen, is accused of making false statements to investigators.

They were remanded in custody as a prosecutor argued they all presented a "serious risk of flight".

If convicted, Mr Kadyrbayev and Mr Tazhayakov face a maximum sentence of five years in prison and a $250,000 (£160,000) fine, while Mr Phillipos faces up to eight years in prison and a similar fine.

According to the affidavit, Mr Tazhayakov and Mr Kadyrbayev removed items from the suspect's dormitory room at the University of Massachusetts - Dartmouth, three days after the blasts.

When TV news reports aired photos of the bombing suspects, released by the FBI, Mr Kadyrbayev allegedly texted Dzhokhar Tsarnaev to say that he resembled the suspect.

Mr Tsarnaev's response included the phrases "lol" and "you better not text me".

According to the charge sheet, he also texted Mr Kadyrbayev: "I'm about to leave if you need something in my room take it."

Mr Kadyrbayev's lawyer said his client did not immediately think that Mr Tsarnaev was the suspect in the FBI images, and that he did not realise the backpack was evidence.

However, the FBI said that Mr Kadyrbayev knew when he saw a backpack containing fireworks which had been opened and emptied of powder that Mr Tsarnaev was involved in the bombings.

Student visas 'violation'

The affidavit says Mr Kadyrbayev told authorities that he and his two co-accused "collectively decided to throw the backpack and fireworks into the trash because they did not want Tsarnaev to get into trouble".

Image caption Tamerlan Tsarnaev's widow, Katherine Russell, has reportedly given consent for his body to be released

Mr Kadyrbayev also decided to remove Mr Tsarnaev's laptop "because he did not want Tsarnaev's roommate to think he was stealing or behaving suspiciously by just taking the backpack", the FBI said in court papers.

Mr Kadyrbayev said he placed the backpack and fireworks along with rubbish from the apartment in a large refuse sack and threw it into a bin near the men's apartment.

Investigators say they later found the backpack, along with a homework assignment sheet from a class that Mr Tsarnaev attended, in a landfill.

The court papers do not say what happened to the laptop.

Mr Tazhayakov said that Mr Tsarnaev had explained to the two Kazakhs a month before the attacks that he knew how to make a bomb, according to the affidavit.

Mr Tazhayakov and Mr Kadyrbayev have been held in jail for more than a week for allegedly violating their student visas.

University of Massachusetts - Dartmouth said in a statement on Wednesday that Mr Tazhayakov had been suspended pending the outcome of the case.

The two other men were not currently enrolled, the university said.

Dzhokhar Tsarnaev, who received gunshot wounds during the police manhunt, faces a possible death sentence if convicted for his alleged role in the bombings.

He remains in a hospital prison.

Tamerlan Tsarnaev's relatives said on Tuesday they would claim his body now that his widow, Katherine Russell, has given consent for the Massachusetts medical examiner to release it, an uncle said.

The Tsarnaev family has origins in the predominantly Muslim republic of Chechnya in southern Russia.