Tesla has increased its capital spending plan by $1 billion, the electric automaker said on Monday in a regulatory filing that also disclosed a second subpoena related to Chief Executive Elon Musk's go-private tweets in 2018. 

The company now expects to spend between $6 billion and $8 billion this year and each of the next two years, up from its previous expenditure plan of $5 billion to $7 billion, as it looks to ramp up production at its new facilities in Texas and Berlin.

Meanwhile, the latest subpoena by the U.S. Securities and Exchange Commission (SEC) on June 13, has sought information about compliance with Musk's settlement with the regulator in 2018. 

The company said it will cooperate with the government authorities. The SEC declined to comment. The regulator had first subpoenaed Tesla in November related to the settlement.

The latest subpoena comes as Musk prepares for a legal showdown in October with Twitter for dropping his $44-billion offer to buy the social media company. 

In June, the regulator had questioned Musk over a tweet in which he raised doubts over his acquisition of Twitter due to concerns over the number of fake users and spam accounts.

Separately, Tesla's filing said it converted about 75 percent of its bitcoin holdings into fiat currency, gaining $64 million in the process, while recording an impairment charge of $170 million in the first six months of 2022. 

As of June 30, the fair market value of its digital assets was worth $222 million, it said in the filing.

(With input from Reuters)