DUBAI, Jan 28 (Reuters) - Shares in Saudi Arabia's Kingdom Holding soared in early trade on Sunday after owner Prince Alwaleed bin Talal was released from detention, but top petrochemical producer Saudi Basic Industries fell on weak fourth-quarter earnings.

The Saudi stock index was flat after an hour but rising stocks outnumbered losers in a ratio of about two to one.

The release of Prince Alwaleed and at least several other senior Saudi businessmen at the weekend, after they were detained for over two months in a corruption probe, was seen as positive for their companies - and also for the market as a whole, by suggesting the probe, which sent shockwaves through political and business circles, was winding down.

Kingdom soared its 10 percent daily limit in unusually heavy trade; it remains 2.3 percent below its level before Prince Alwaleed was detained in early November, and since then, the market index has gained 8.2 percent.

The terms of the release of Prince Alwaleed and the other businessmen were not disclosed. A Saudi official said they had agreed to financial settlements after unspecified violations.

But Prince Alwaleed told Reuters that he had continued to maintain his innocence of any wrongdoing and did not expect to have to give up any assets. This suggested to investors that his company might not be seriously damaged by the affair.

Shares in Saudi fashion retailer Fawaz Abdulaziz Alhokair Co , whose major shareholder Fawaz Alhokair was also detained and then released at the weekend, jumped 6.6 percent in heavy trade.

The market index was weighed down, however, by a 2.3 percent drop by SABIC, which reported that quarterly net profit fell to 3.67 billion riyals ($979 million) from 4.51 billion riyals a year ago. SICO Bahrain had projected 5.34 billion riyals and NCB Capital, 5.41 billion riyals.

SABIC attributed the fall in profit to planned turnarounds at certain plants, which hit output, and also noted that 2016's quarterly profit was helped by recognition of deferred tax assets.

Yanbu National Petrochemicals rose 1.4 percent, however, after reporting fourth-quarter profit of 778 million riyals, up 28 percent and beating SICO Bahrain's forecast of 634 million riyals and NCB Capital's 677 million riyals.

Saudi Telecom also beat estimates with a rise of fourth-quarter net profit to 2.65 billion riyals from 2.08 billion riyals; its shares climbed 2.5 percent.

The rest of the Gulf was sluggish. Dubai's index edged down 0.1 percent, Abu Dhabi was down 0.2 percent and Qatar lost 0.5 percent.

Qatari real estate firm Ezdan, which had tumbled 6.8 percent on Thursday after reporting a drop in annual profit and halting its dividend, fell a further 2.2 percent.

But drilling rig provider Gulf International Services , the most heavily traded stock, climbed 3.3 percent to 20.45 riyals on the back of strong oil prices. It touched but then pulled back from technical resistance on the September peak of 20.99 riyals. (Reporting by Andrew Torchia)