Business software maker Oracle has agreed to buy competitor Siebel Systems for 5.8 billion dollars, the companies said in a statement carried by dpa Monday. The deal makes Oracle the world's leading vendor of software systems for handling customer relationship management, or CRM, giving it a dominant position in the fastest growing sector of business applications. Oracle said its acquisition will add 4,000 customers and 3.4 million CRM users. Oracle will offer 10.66 dollars for each share of Siebel stock, a nearly 17 per cent premium over the company's 9.13-dollar closing price Friday. The purchase is Oracle's seventh this year as CEO Larry Ellison tries to diversify away from the company's reliance on database software. The most notable purchase was the 10.6-billion dollar hostile takeover of PeopleSoft in January. Sebel Systems was founded by former Oracle executive Tom Siebel in 1993 but had been struggling to compete in recent years with German software giant SAP. --More 2259 Local Time 1959 GMT