LA JOLLA, CALIF., OCT. 28 -- Henley Group Inc., whose efforts to acquire a portion of Santa Fe Southern Pacific Corp. collapsed earlier this month, said today it has increased its stake in the transportation and natural resources concern to 14.1 percent from 5 percent.

Henley, which has received federal approval to buy up to 24.9 percent of Santa Fe Southern, increased its holdings as Wall Street's collapse sharply reduced stock prices.

In a filing with the Securities and Exchange Commission, Henley also said it "reserves the right to take whatever action may be necessary" to enhance shareholder value, including acquiring control of Santa Fe Southern or seeking seats on its board.

Henley, a conglomerate of engineering and financial services companies spun off from Allied-Signal Inc. in 1985, also said it is preparing a proposal for merging Henley and Chicago-based Santa Fe Southern.

Santa Fe Southern spokesman Robert Gehrt said the Chicago company had no comment.

In a defensive move last month, Santa Fe Southern said it intended to repurchase about 38 percent of its stock.

On Oct. 19, Santa Fe Southern's stock lost nearly 19 percent of its value, dropping $9.62 1/2 per share to $41.37 1/2. In the past year, the company's stock has traded as high as $65 and as low as $29.37 1/2.

The price paid by Henley for its purchases over six days beginning Oct. 19 ranged from $41.09 to $52.68 per share.

Santa Fe Southern was formed in 1983 by the merger of Chicago-based Santa Fe and San Francisco-based Southern Pacific. But the merged company continued to operate its two railroad lines separately, pending government approval.

Earlier this year, the Interstate Commerce Commerce refused to permit combination of the railroads and ordered Santa Fe Southern to sell one of them.

With a breakup looming, Santa Fe Southern became a lucrative takeover target. One of its main attractions is extensive land holdings, much of which are controlled by the Southern Pacific unit.