Britney Spears and Sam Asghari are officially married ... despite weird interruption from her ex

Britney Spears has married fiancé Sam Asghari, seven months after being freed from a conservatorship that she said had prevented her from getting wed.

The couple tied the knot in an intimate ceremony in California on Thursday.

But preparations were disrupted when Jason Alexander, who was briefly married to the pop star in 2004, was arrested after allegedly gatecrashing.

He streamed video on Instagram Live before the ceremony apparently from inside her home before being tackled.

Ventura County Sheriff's Department told the PA Media news agency an altercation had taken place with security officers, and Mr Alexander had been charged with four misdemeanour offences of trespassing, battery and vandalism.

"He was able to find his way onto the property and was confronted by security," a police spokesman said.

"An altercation occurred with the security officers and that's where the battery occurred... and during the altercation an item was broken, so that's where the vandalism comes into play. And by being on private property, the trespass comes into play."

Mr Alexander was married to Spears, his childhood friend, for less than 55 hours in 2004 before it was annulled.