MINNETONKA, Minn. (AP) _ The folks at Hasbro Inc. might be needing a bigger toy box.

The maker of Milton Bradley board games, Playskool toys, G.I. Joe, Transformers and My Little Pony agreed Thursday to buy Tonka Corp. Aside from the toy trucks, Tonka makes Parker Brothers board games, Play-Doh, Nerf and Spirograph.

''This will give Hasbro the broadest product line in the toy business,'' said David Lebowitz, a toy industry analyst with American Securities Corp. ''It will make Hasbro all but a one-stop shopping point for buyers coming to Toy Fair,'' the toy industry's annual trade show.

Pawtucket, R.I.-based Hasbro also holds the license for Cabbage Patch Kids dolls. One of Hasbro's biggest successes this past Christmas was a line of dolls based on the New Kids on the Block rock group.

In board games, Lebowitz said, Tonka's Parker Brother's Monopoly, Trivial Pursuit and other popular games are second only to Hasbro's Milton Bradley with Scrabble, Yahtzee, Scruples and the children's game Candyland.

The deal would make Hasbro ''hands-down number one in board games,'' Lebowitz said.

Hasbro is the nation's top toymaker. Tonka and Mattel Inc. trail.

The exact value of the deal was unclear. But the companies said in a joint statement that Hasbro would pay $107.1 million in cash for Tonka and assume all of its debts.

The companies said in their statement that they had reached a definitive agreement under which Hasbro would begin a $7-per-share tender offer for all of Tonka's 15.3 million outstanding shares. Tonka would become a wholly owned Hasbro subsidiary at the completion of the tender offer.

Hasbro said it would pay for the acquisition out of its cash on hand and from money available under its existing credit agreements.

Tonka said its board of directors already has approved the acquisition.

B.J. French, a Tonka spokeswoman, declined to say Thursday how long Tonka and Hasbro negotiated and which one initiated the talks. Hasbro officials also declined to comment beyond the joint statement.

Both Hasbro and Tonka were hurt in 1990 by the same malaise suffered by many other toy manufacturers. Parents, worried about the economy and the Middle East crisis, cut back on the number of toys they gave their children at Christmas.

''The combined entity will be better able to compete in the increasingly more competitive international marketplace,'' said Alan G. Hassenfeld, Hasbro's chairman and chief executive officer.

Tonka also has suffered recently from a dearth of successful new products. Some of its biggest sellers in past years, Pound Puppies plush toys and Real Ghostbusters action figures, reached their peak and then went into a decline without Tonka having well-received products to replace them.

The company has struggled for much of the time since acquiring Kenner Parker Toys Inc. in 1987, when its long-term debt rose from $8.2 million in 1986 to $526.2 million.

Tonka reported $5.7 million in earnings in 1989, the first time in three years it had earned a profit.

But it said Monday that it expects sales to decline 10 percent, from $870.5 million in 1989 to $786 million in 1990.

Hasbro reported earnings of $61.3 million during the first three quarters of 1990, down 10 percent from a year earlier. Sales totaled $1.03 billion.

Hasbro has about 8,200 employees after laying off about 6 percent of its corporate staff last year. It also decided at the time to spend less on research and development.