AUSTIN, Texas (AP) _ The Texas House speaker was indicted on charges he accepted $5,000 from a law firm and didn't disclose it, joining legislative leaders in the two other most populous states under an ethical cloud.

House speakers in New York and California also are under scrutiny as they prepare for new legislative sessions. The investigation in Texas also involves other legislators.

A Travis County grand jury returned indictments on two misdemeanor charges Friday against Gib Lewis, alleging he solicited and received a gift from the San Antonio-based law firm of Heard Goggan Blair & Williams, then failed to report it.

Despite the charges, Lewis' lawyer said the lawmaker would seek an unprecedented fifth term as House speaker.

''I don't see any legal reason or otherwise why he shouldn't be elected to the speakership,'' attorney Bill Willms said.

The 150-member House will elect a speaker Jan. 8, the first day of the regular legislative session.

The first charge alleges the law firm paid part of a tax bill Lewis owed. The second claims he failed to disclose the payment as a gift on his public financial disclosure statement.

The maximum penalty upon conviction of both charges is 1 1/2 years in jail and a $3,000 fine.

''Although these crimes are misdemeanors, they are among the most serious crimes a public official can be charged with,'' prosecutor Ronnie Earle said Friday.

Lewis, a Fort Worth Democrat, has denied any wrongdoing, and his lawyers said he would plead innocent. Lawyer Allen Hill and other defense attorneyes said the charges were politically motivated.

Lewis, 54, was traveling and unavailable for comment on the indictment, said his spokesman, Monte Williams.

The grand jury, which will remain in session for another three months, also is investigating an April 1987 trip to Mexico that Lewis took with four partners in the law firm, an Austin lobbyist and six women, one of whom reportedly was a topless dancer named Chrissee.

''There are a number of allegations remaining under investigation concerning Mr. Lewis, various members of the Legislature and lobbyists,'' Earle said.

Heard Goggan, one of the few law firms in Texas with contracts to collect delinquent taxes for local governments, paid about half of a $10,433 delinquent tax bill owed by a company partly owned by Lewis, the indictment claims. Lewis has said the payment represented a ''business settlement.''

As speaker for the last eight years, Lewis has controlled the House, assigning bills to committees, naming their chairmen and directing floor debate.

Earle said the indictments were issued Friday to meet the statute of limitations on misdemeanor charges and because of the upcoming election for House speaker.

In the past eight years, the law firm has flourished under a state law that allows a private firm hired by local governments to add a 15 percent fee onto overdue tax bills.

Numerous legislative attempts aimed at changing the law have died in House committees.

In New York, Assembly Speaker Mel Miller pleaded innocent Dec. 20 to federal mail fraud charges involving allegations of a real estate scam.

Miller, a Democrat from New York City, and top aide and former law partner Jay Adolf were indicted on 19 counts of mail fraud, conspiracy and falsifying documents.

The charges stem from Miller's private law practice and Miller claims they amount to a political witch hunt.

California Assembly Speaker Willie Brown reportedly is being investigated about allegations that he was involved in legislation aimed at helping a regional garbage company get around local restrictions on landfills. Brown has not been charged with any crime and denies any impropriety.